Report of the ICES Advisory Committee, 2009

Transcription

1 ICES ADVICE 2009 AVIS DU CIEM Books 1-11 Report of the ICES Advisory Committee, 2009 Book 6 North Sea International Council for the Exploration of the Sea Conseil International pour l Exploration de la Mer

2 H.C. Andersens Boulevard DK-1553 Copenhagen V Denmark Telephone (+45) Telefax (+45) info@ices.dk Report of the ICES Advisory Committee Books 1-11 December 2009 Recommended format for purposes of citation: ICES Report of the ICES Advisory Committee ICES Advice, Book 6, 236 pp. For permission to reproduce material from this publication, please apply to the General Secretary. ISBN

3 BOOK 6 Section Page 6 NORTH SEA Ecosystem Overview The human impacts on the ecosystem Fishery effects on benthos and fish communities Assessments and advice Assessments and advice regarding protection of biota and habitats Assessment and advice regarding fisheries Special requests EC and Norway request on in-year management advice for sandeel in the North Sea Stock summaries Cod in Division IIIa East (Kattegat) Cod in Subarea IV (North Sea), Divison VIId (Eastern Channel) and IIIa West (Skagerrak) Haddock in Subarea IV (North Sea) and Division IIIa West (Skagerrak) Whiting in Division IIIa (Skagerrak Kattegat) Whiting in Subarea IV (North Sea) and Division VIId (Eastern Channel) Plaice in Division IIIa (Skagerrak Kattegat) Plaice in Subarea IV (North Sea) Plaice in Division VIId (Eastern Channel) Sole in Division IIIa (Skagerrak Kattegat) Sole in Subarea IV (North Sea) Sole in Division VIId (Eastern Channel) Saithe in Subarea IV (North Sea) Division IIIa (Skagerrak) and Subarea VI (West of Scotland and Rockall) Nephrops in Division IIIa (Skagerrak Kattegat) Nephrops in Division IV (North Sea) Nephrops in Moray Firth (FU 9) Nephrops in Noup (FU 10) Nephrops in Fladen Ground (FU 7) Nephrops in Norwegian Deeps (FU 32) Nephrops in Farn Deeps (FU 6) Nephrops in Firth of Forth (FU 8) Nephrops in Botney Gut Silver Pit (FU 5) Nephrops off Horn s Reef (FU 33) Herring in Division IIIa and Subdivisions (Western Baltic spring spawners) Herring in Subarea IV and Divisions IIIa and VIId (North Sea autumn spawners) Sprat in Division IIIa (Skagerrak Kattegat) Sprat in the Subarea IV (North Sea) Horse mackerel (Trachurus trachurus) in Divisions IIIa, IVb,c and VIId (North Sea stock) Norway pout in Subarea IV (North Sea) and Division IIIa (Skagerrak Kattegat) Sandeel in Division IIIa (Skagerrak Kattegat) Sandeel in Subarea IV excluding the Shetland area Sandeel in Division IVa North of 59 N and West of 0 E (Shetland area) Northern shrimp (Pandalus borealis) in Division IVa (Fladen Ground) Northern shrimp (Pandalus borealis) in Divisions IIIa West and IVa East (Skagerrak and Norwegian Deeps) Demersal elasmobranchs in the North Sea, Skagerrak, and Eastern Channel ICES Advice 2009, Book 6 i

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5 6 NORTH SEA 6.1 Ecosystem overview This Section has not been updated in The most recent ecosystem overview is available in ICES Advisory Report 2008, Section 6.1. This overview can also be found on the ICES website: Human impacts on the ecosystem Fishery effects on benthos and fish communities This Section has not been updated in The most recent description on Fishery effects on benthos and fish communities is available in ICES Advisory Report 2008, Section 6.2. This description can also be found on the ICES website: Assessments and Advice Assessment and advice regarding protection of biota and habitats In 2009, ICES has not provided advice regarding protection of biota and habitats for this area Assessments and Advice regarding fisheries In 2007 the timing of the advisory process for the North Sea was changed at the request of ICES clients. This means that the fisheries advice is delivered in the first half of the year instead of in October. To evaluate whether new information that becomes available after the advice is released would form a basis to update the advice ICES has developed a generic approach (AGCREFA, 2008a). The approach is based on a statistical evaluation of the importance of that information (e.g. new survey information available in August/September). The state and the limits to exploitation of the individual stocks are presented in the stock sections. The state of the North Sea stocks and single-stock exploitation boundaries are summarized in table below. For the stocks of elasmobranchs (rays, skates, sharks), Nephrops in Division IIIa, and deep-water species, ICES provides advice every second year. The 2008 advice for these stocks can be found in table and and is valid for both 2009 and Mixed fisheries and fisheries interactions This Section has not been updated in The most recent description on Mixed fisheries and fisheries interactions is available in ICES Advisory Report 2008, Section 6.3. This description can also be found on the ICES website:. Sources of information ICES. 2008a. Report of the Ad hoc Group on Criteria for Reopening Fisheries Advice (AGCREFA), August 2008, Copenhagen, Denmark. ICES CM 2008/ACOM:60. ICES. 2008b.ICES Advisory Report 2008, Book 6. ICES Advice 2009, Book 6 1

6 2 ICES Advice 2009, Book 6 Single-stock exploitation boundaries and critical stocks Table Single stock advice for North Sea stocks, summary of state of stocks and single-stock exploitation boundaries. The state and the limits to exploitation of the individual stocks are presented in the stock sections. Stocks State of the stock ICES considerations in relation to single-stock exploitation boundaries Upper limit Cod in Kattegat Cod in the North Sea, Eastern Channel and Skagerrak Haddock in the North Sea and Division IIIaN Whiting in Division IIIa Whiting in the North Sea and Eastern Channel Plaice in Division IIIa Plaice in the North Sea Spawning biomass in relation to precautionary limits Reduced reproductive capacity Reduced reproductive capacity. Full reproductive capacity. Fishing mortality in relation to precautionnary limits Fishing mortality in relation to high longterm yield Fishing mortality in relation to agreed management target In relation to agreed management plan Unknown Unknown Unknown F reduction of 25% cannot be reliably estimated, thus a 25% TAC reduction: 379 t Increased risk Harvested sustainably Overfished Appropriate Above target. Below target Assuming efficient enforcement (F reduction and effort control), the management plan implies landings of less than t Landings of t (15% TAC reduction, including industrial bycatch). in relation to precautionary limits No catches of this stock No catches of this stock, stock cannot rebuild to B pa even with zero catches Human consumption landings < t bring the stock down to B pa. in relation to high longterm yield corresponding to single-stock exploitation boundary. Tonnes or effort in 2010 Zero catches. F is above F HCR = 0.4. < t, assuming efficient enforcement F is below F HCR = t, including industrial bycatch. No change in the perception of the stock Same advice as last year < 1050 t, recent average landings. Undefined Undefined Overfished Significant reduction Significant of TAC to remedy reduction of SSB decline in SSB (-64% to stabilize SSB < HC catch) No change in the perception of the stock Same advice as last year < 9400 t Full reproductive capacity. Harvested sustainably Overfished Below target A maximum reduction of 15% in the TAC corresponds to landings of t. Catches < t corresponding to F pa. F is above F max. 2 ICES Advice 2009, Book t

7 ICES Advice 2009, Book 6 3 Stocks State of the stock ICES considerations in relation to single-stock exploitation boundaries Upper limit Plaice in the Eastern Channel Sole in Division IIIa Sole in the North Sea Sole Eastern Channel Saithe in the North Sea, Division IIIa and Subarea VI Herring in IIIa and Subdivisions (spring spawners) Herring in the North Sea, VIId and IIIa (autumn spawners) Sprat in Division IIIa Spawning biomass in relation to precautionary limits Fishing mortality in relation to precautionnary limits Fishing mortality in relation to high longterm yield Fishing mortality in relation to agreed management target In relation to agreed management plan ICES Advice 2009, Book 6 3 in relation to precautionary limits Unknown Unknown Unknown Unknown Recent average landings < t Full reproductive capacity. Full reproductive capacity. Full reproductive capacity. Full reproductive capacity. Harvested sustainably Harvested sustainably Increased risk Harvested sustainably Appropriate Appropriate Overfished Above target No agreed target. A 10% reduction in fishing mortality would lead to landings of t. Appropriate Appropriate A maximum reduction of 15% in the TAC corresponds to landings of t Catches < 620 t corresponding to F pa. Catches < t corresponding to F pa. Catches < t corresponding to F pa. Landings < t to retain the stock above B pa in relation to high longterm yield F is above the range of candidate reference points. F is above the range of candidate reference points. F is close to the candidate reference point. Undefined Undefined Overfished Catches < t corresponding to candidate reference point F = 0.25 Increased risk. Harvested sustainably Overfished Above target. Following the management plan catches for fleet A < t fleet B < t F is above candidate reference points corresponding to single-stock exploitation boundary. Tonnes or effort in 2010 < t < 620 t < t < t t < t fleet A < t fleet B < t, see scenario s No change in the perception of the stock Same advice as last year Limit by restriction on juvenile herring catch.

8 4 ICES Advice 2009, Book 6 Stocks State of the stock ICES considerations in relation to single-stock exploitation boundaries Upper limit Sprat in the North Sea Norway pout North Sea Nephrops in Subarea IV, FU6 Nephrops in Subarea IV, FU7 Nephrops in Subarea IV, FU8 Nephrops in Subarea IV, FU9 Nephrops in Subarea IV, 'Other areas' Sandeel in Division IIIa Sandeel North Sea Sandeel in Shetland area Pandalus in the Fladen Ground Spawning biomass in relation to precautionary limits Fishing mortality in relation to precautionnary limits Fishing mortality in relation to high longterm yield Fishing mortality in relation to agreed management target In relation to agreed management plan in relation to precautionary limits Unknown Unknown Unknown No basis for numerical advice, recent catch has created no problems Full reproductive capacity. in relation to high longterm yield corresponding to single-stock exploitation boundary. Tonnes or effort in 2010 No advice Undefined Undefined Maintain SSB > Bpa. < t. Unknown Unknown Unknown Landings < t, Harvest rate should not exceed F 2008 Unknown Unknown Unknown Landings < t, Harvest rate should not exceed F 0.1 Unknown Unknown Unknown Landings < t, Harvest rate should not exceed F max Unknown Unknown Unknown Landings < t, Harvest rate should not exceed F 2008 Unknown Unknown Unknown Recent average landings < t, ( ) Increased risk Insufficient information to evaluate stock trends. Undefined Undefined Fishery should only be allowed if monitoring shows the stock can rebuild to B pa by 2011 Insufficient information to evaluate stock trends. Insufficient information to evaluate stock trends < t and manage on stock basis < t and manage on stock basis < t and manage on stock basis < t and manage on stock basis < t No advice. In year monitoring No advice. No advice. 4 ICES Advice 2009, Book 6

9 ICES Advice 2009, Book 6 5 Stocks State of the stock ICES considerations in relation to single-stock exploitation boundaries Upper limit Pandalus in the Skagerrak and Norwegian Deep Mackerel in the North Sea Horse mackerel in the North Sea Spawning biomass in relation to precautionary limits Fishing mortality in relation to precautionnary limits Fishing mortality in relation to high longterm yield Fishing mortality in relation to agreed management target In relation to agreed management plan ICES Advice 2009, Book 6 5 in relation to precautionary limits Unknown Unknown Undefined No increase in landings above 2008 level ICES advises that the existing measures to protect the North Sea spawning component remain in place. in relation to high longterm yield corresponding to single-stock exploitation boundary. Tonnes or effort in 2010 < t Lowest practical level No change in the perception of the stock Same advice as last year. TAC < t.

10 6 ICES Advice 2009 Book 6 Table North Sea stocks with biennial advice. The advice from 2008 is valid for 2009 and The state and the limits to exploitation of individual stocks are presented in the stock sections available on ICES 2008b. Stocks State of the stock ICES considerations in relation to single-stock exploitation boundaries Upper limit Nephrops in Division IIIa (FUs 3 and 4) Nephrops in Subarea IV, FU5 Nephrops in Subarea IV, FU10 Spawning biomass in relation to precautionar y limits Fishing mortality in relation to precaution ary limits Fishing mortality in relation to high long-term yield Fishing mortality in relation to agreed manageme nt target In relation to agreed management plan in relation to precautionary limits Unknown Unknown Unknown There are no signs of decline in the stocks and therefore current levels of exploitation and effort appear to be sustainable in relation to high long-term yield corresponding to single-stock exploitation boundary. Tonnes or effort in 2010 Current effort appears to be sustainable Unknown Unknown Unknown No increase in effort. No increase in effort. Unknown Unknown Unknown No increase in effort < 240 t and no and average landings increase in effort. ( ). Nephrops in Subarea IV, FU32 Unknown Unknown Unknown No increase in effort. No increase in effort. Nephrops in Subarea IV, FU33 Unknown Unknown Unknown No increase in effort. No increase in effort. Demersal elasmobranchs in the North Sea Combined * Unknown Unknown Unknown Combined catches for demersal skates and rays should be set on the basis of the recent average landings ( ). Subject to the individual recording of landed species, no targeted fisheries and minimal bycatch of common skate and undulate ray and no landings of angel shark. < 3100 t Spurdog ** The stock is depleted and may be in danger of collapse. The advice for 2009 and 2010 is the same as the advice given in 2006: Targeted fisheries should not be permitted to continue, and bycatch in mixed fisheries should be reduced to the lowest possible level. The TAC should cover all areas where spurdog are caught in the northeast Atlantic and should be set at zero (...).. Zero catches, low bycatch. * See table Demersal elasmobranchs in the North Sea by species ** Spurdog advice is presented in ICES 2008b Section ICES Advice 2009, Book 6

11 ICES Advice 2009, Book 6 7 Table Individual advice for demersal elasmobranchs in the North Sea. The advice from 2008 is valid for 2009 and Species Area State of stock Advice Common skate IVa (likely merging with VIa&IIa) Depleted No target fisheries Thornback ray IVc, VIId Stable/increasing Status quo catch IVa,b Uncertain No advice Spotted ray IVb,c Stable/increasing Status quo catch Starry ray IVa,b, IIa Stable Status quo catch Cuckoo ray IVa,b Stable Status quo catch Blonde ray IVc, VIId Uncertain No advice Undulate ray VIId, merges with VIIe Uncertain, reasons for No target fisheries concern Lesser-spotted dogfish IVa,b,c, VIId Increasing Status quo catch Smooth hound & IVa,b,c, VIId Increasing Status quo catch Starry smooth hound Angel shark IVa,b,c, VIId Extirpated No fisheries ICES Advice 2009, Book 6 7

12 6.3.3 Special Requests EC and Norway request on in-year management advice for sandeel in the North Sea The European Community (EC) and Norway requested ICES to provide further advice to allow EC to apply the procedure described in COUNCIL REGULATION (EC) No 43/2009, ANNEX IID. ICES understands the method referred to in the request as the method for setting the TAC for sandeel in the North Sea as suggested by ICES in its advice on harvest control rules and long-term management strategies for sandeels (ICES Advice, 2007, 2008a) and that the TAC calculated by this method shall apply to all catches of sandeel (EC and Norway). Annex IID prescribes a Real-Time Monitoring (RTM) fishery of sandeel during weeks 14 to 18 in 2009 to estimate the abundance and mean weight of the 2008 year class. These estimates are used in the formula TAC 2009 = * N1 * (W obs / W m ) where N1 is the real-time estimate of age group 1 sandeel in billions derived from the exploratory fishery in 2009; the TAC is expressed in 1000 tonnes; W obs is the observed mean weight of age group 1 during the exploratory fishery; and W m (3.8 g) is the long-term mean weight of an age 1 sandeel. The estimation of the year class (N1) is as previously outlined in ICES (2007) and ICES (2008a). ICES response Based on real-time monitoring data from weeks 14 to 18 in 2009, the estimated stock size estimate of age 1 sandeels in 2009 is approximately 130 billion individuals and the estimated mean weight of an age 1 sandeel in 2009 is 6.11 g. Adjusting for over-sampling along the Danish coast, these estimates become approximately 118 billion individuals and 5.86 g, respectively. Using these corrected estimates, the calculated 2009 TAC value based on the formula above is t, higher than the agreed maximum TAC of t. Therefore, the total 2009 TAC (for EC and Norway combined) for sandeel in the North Sea should be tonnes as specified in the agreement. However, there are concerns about the applicability of this approach to TAC-setting which is based on the invalid assumption that there is a single stock of sandeel in the North Sea. Technical background to the ICES response This response is based on 2009 data from the Danish fishery (extracted from the Danish Fishery Directorate s database on 5 May 2009) and the Norwegian fishery (received from IMR 5 May 2009). This year the data pertain only to the main historical fishing grounds in the EU EEZ, as the sandeel fishery has been closed in the Norwegian EEZ. Total landings of t, including 5700 t Norwegian landings, have been reported so far this year. Logbook information from 108 trips and data from 83 biological samples of sandeel landings obtained between 1 April and 4 May 2009 were used to estimate the abundance of the 2008 cohort of sandeels at age 1. International landings during April-May 2009 were concentrated in a band stretching from the Dogger Bank area to the coast of the northern Jutland. This spatial distribution of landings is similar to that observed last year and is more concentrated than in 2004, 2006 and The maps in Figure indicate the spatial distribution of the sandeel harvests and samples during weeks in Based on real-time monitoring data from weeks 14 to 18 in 2009, the estimated stock size estimate of age 1 sandeels in 2009 is approximately 130 billion individuals and the estimated mean weight of an age 1 sandeel in 2009 is 6.11 g. Landings from the area along the Danish coast (e.g. rectangle 42F7 and 43F7) were over-sampled relative to landings from other areas as the Danish coast area is fished by relatively small vessels on day-trips, resulting in a high number of trips per tonne of landings. Adjusting for this over-sampling, both the 1-group estimate of stock size and mean weight are reduced (approximately 118 billion individuals and 5.86 g, respectively); leading to a calculated value according to the agreed procedure described in COUNCIL REGULATION (EC) No 43/2009, ANNEX IID of t, slightly greater than the agreed maximum TAC of t. The standardized catch per unit of effort (cpue) in 2009 was relatively stable over the monitoring period varying from 47 t day 1 in week 14 to 52 t day 1 in week 18. Statistics for age 1 sandeel in 2009 are presented below. Values by weeks are based on cumulative data, including the given week. 8 ICES Advice 2009, Book 6

13 Week number Dates (day/month day/month) Cumulative Mean weight (g) Cumulative cpue (number caught per standardized day absent) Cumulative Estimated age 1 sandeel numbers in the sea (billions) /04 15/ /04-22/ /04-29/ /04-04/ The sandeel fishery in 2009 was concentrated in three rectangles which accounted for about 70% of all landings. ICES reiterates its past observation that fisheries can cause local depletion of sandeel. Sandeel management in the North Sea is based on the invalid assumption that there is a single stock. There is strong evidence of a number of spatially distinct (sub-) stocks, although the full stock structure of sandeel in the North Sea remains unclear. It is known that sandeel (sub-) stocks on the Viking/Bergen Banks and in the western North Sea off Scotland are distinct, as is the (separatelymanaged) Shetland stock. Current knowledge for defining (sub-) stocks off south-west Norway and in the southern North Sea is too limited to recommend specific management measures for 2009 which can take into account the full stock structure of sandeel in the region. The model in Annex IID of COUNCIL REGULATION (EC) No 43/2009 was developed based on a more widely distributed fishery yearly landings for the period distributed by ICES rectangle are shown in Figure In 2009, the restricted spatial distribution of the fishery raises concerns about the validity of the current modelling approach and its reliance on a single index. These concerns further strengthen the argument for future spatial management in the sandeel fishery. Source of information ICES ICES Advice, Copenhagen, Denmark. ICES. 2008a. ICES Advice, Copenhagen, Denmark. ICES. 2008b. Report of the Working Group on the Assessment of Demersal Stocks in the North Sea and Skagerrak Combined Spring and Autumn (WGNSSK). ICES CM 2008/ACFM:09 ICES Report of the Ad hoc Group on Sandeel (AGSAN). Copenhagen, Denmark. ICES Advice 2009, Book 6 9

14 Figure Landings weight from all available trips (left hand panel) and number of biological samples (right hand panel) by ICES rectangle for the Danish and Norwegian North Sea sandeel fishery. The area of the bubbles illustrates landings weight. The total landings weight (total:) and the maximum landing weight (max:) per rectangle are given as text (unit 1000 tonnes). The total and maximum number of samples by ICES rectangle are presented in the right hand panel (From ICES AGSAN 2009). 10 ICES Advice 2009, Book 6

15 Figure Sandeel in Subarea IV. Landings of sandeel by year and ICES rectangles for the period Landings include Danish and Norwegian landings for the whole period. Scottish landings are included from 1997 onwards; Swedish landings are included from Landings from other countries are negligible. The area of the circles corresponds to landings by rectangle. All rectangle landings are scaled to the largest rectangle landings shown in the 1995 map. The area that was closed to the sandeel fishery in 2000 and the boundary between the EU EEZ and the Norwegian EEZ are shown on the map (From ICES WGNSSK 2008b). ICES Advice 2009, Book 6 11

16 6.4 Stock Summaries Cod in Division IIIa East (Kattegat) State of the stock Spawning biomass in relation to precautionary limits Reduced reproductive capacity Fishing mortality in relation to precautionary limits Fishing mortality in relation to high long-term yield Fishing mortality in relation to agreed target Unknown Unknown Unknown Comment Based on the most recent estimates of SSB (in 2009) ICES classifies the stock as suffering reduced reproductive capacity. The SSB trend indicates a fivefold decrease since 1970 and SSB has been at a historically low level since the early 2000s. Current level of fishing mortality is unknown. Recruitment in recent years has been the lowest in the time series. Management objectives In 2004, the European Commission enacted a Council Regulation (EC) No. 423/2004 which established measures for the recovery of cod stocks, including cod in the Kattegat. Council Regulation (EC) No 1342/2008 of 18 December 2008 (see Annex 6.4.1) established a long-term plan for cod stocks and the fisheries exploiting those stocks, repealing Regulation (EC) No 423/2004. The long term management plan requires implementation through Article 9 due to the current inability to estimate F. An exploratory evaluation (see section below) that assumed no bias in the TAC implementation shows that SSB will recover before 2015 to within precautionary limits; however, this evaluation is not expected to be realistic in a situation where unaccounted removals may be up to five times the TAC. In these circumstances ICES considers that a TAC constraint alone (under Article 9) is not precautionary. Reference points Type Value Technical basis B lim t lowest observed SSB before the late 1990s. Precautionary B pa t B lim *exp(1.645*0.3). approach F lim Not defined F pa Not defined Targets F mgt 0.4 EU management plan EC 1342/08 (unchanged since 2009) Single-stock exploitation boundaries Considering the options below, ICES advises on the basis of Exploitation boundaries in relation to precautionary considerations that there should be no catches of this stock in Exploitation boundaries in relation to existing management plans According to the long-term management plan, the fishing mortality in 2010 shall be reduced by 25 % compared with the fishing mortality rate in 2009, unless the target 0.4 is reached. The current level of fishing mortality on cod in the Kattegat cannot be reliably estimated. Where it is advised that the catches of cod should be reduced to the lowest possible level, the TACs shall be set according to a 25 % reduction compared to the TAC in the previous year, that corresponds to a TAC at 379 tonnes in Exploitation boundaries in relation to precautionary considerations Taking into account the current perception of the stock abundance and recruitment, fishing at any level will involve a risk of the stock remaining depleted. 12 ICES Advice 2009, Book 6

17 Short-term implications Due to uncertainty in the recent estimates, especially concerning fishing mortality, reliable predictions cannot be made. Management considerations Even though a management plan has been in place since 2005, the stock biomass has continued to decline. Total removals in the last 3 years have been estimated up to 5 times higher than the reported catches. No information is available on the nature of the unallocated removals but this information is essential to managers in order to take the appropriate management measures. Potential sources of unallocated removals are discarding of young ages and possibly also high-grading of marketable cod. Furthermore, migration of cod to other areas and not counted catches in recreational fisheries may explain the discrepancy between the reported catches and the estimates of total removals. Management plan evaluations ICES has conducted exploratory evaluation of the long-term management plan for cod in the Kattegat as specified by Council Regulation (EC) No 1342/2008 of 18 December The results showed that the present low TAC and the 20% TAC constraint in the long-term plan will allow a steep increase of SSB to above B pa even though scenario recruitment is assumed to be at a low level. This conclusion is based on no bias in the TAC implementation, which is not expected to be realistic. Due to uncertainties related to the historical and future bias in catch reporting and the extend of inflow of recruits from the North Sea stock and their homing at age 2-3 it is not possible to quantify the effect on the SSB of the local Kattegat stock spawning in the area. Factors affecting the fisheries and the stock Regulations and their effects Cod in Kattegat are mainly taken by trawls, Danish seines and gill-nets, Since 2004, the use of trawl with codend mesh sizes below 90 mm in the Nephrops fisheries has only been permitted if the trawl was equipped with a separator grid. This has resulted in a substantial decline of effort for this gear category. In 2007, Danish fishermen were allocated extra fishing days if using an exit-window with square-meshes at a minimum 120 mm; since 1 st February 2008, the usage of the exit-window in trawls has been made mandatory. The Danish minimum landing size was reduced to 30 cm in February In 2008, due to effort restrictions imposed between 1 February and 30 April the usage of trawls equipped with species sorting grid (which allows most cod to escape from the trawl) increased considerably, as this type of trawl is not effort regulated. These changes can be expected to have reduced discard of undersized cod, the effect can however not be evaluated due to uncertain discard estimates. Changes in fishing pattern in 2008 are believed to have reduced Swedish discards in Spatial and temporal fishing area closures were implemented in the Kattegat in January 2009 in order to reduce fishing mortality on cod. The effects of the spatial restrictions on cod recovery will be evaluated in three years time after the implementation. Impacts of the environment on the fish stock An analysis of the possible effect of environment and climate change on this stock has shown that fishing mortality has been the major driver of the long-term dynamics of the stock (Cardinale and Svedäng, 2004). Scientific basis Data and methods Reported landings and data from four scientific surveys were available for the assessment of this stock. Discard data are not used the assessment. The assessment is based on the recently developed stochastic state-space model (SAM) that provides statistically sound estimates of uncertainty in the model results. The model allows estimating potential additional removals from the stock, not represented by reported landings. The stock estimates for these years consequently rely more on survey information. The model estimates significant unallocated removals from the stock between 2003 and At present, the relative proportion of unallocated removals due to fishing and biology driven factors (migration patterns) cannot be specified. Therefore, both runs with and without estimating unallocated removals are presented (Figure ). Estimates of F in either runs are not considered reliable. ICES Advice 2009, Book 6 13

18 Information from the fishing industry In December 2008, an extensive joint Swedish-Danish cod survey in Kattegat was conducted as collaboration between the fishing industry and fisheries research institutes of Denmark and Sweden. The data from this survey were used to provide an independent estimate of biomass of adult cod in the Kattegat (WKROUND 2009). The results were in line with the estimates from assessment, indicating low SSB (below 2000 tonnes). Uncertainties in assessment and forecast In recent years, reported landings appeared not to represent total removals from the stock. Significant bias in removals was estimated for At present, the relative proportion of unallocated removals due to fishing and biology driven factors cannot be specified. Recent tagging studies suggest that the Kattegat may function as a nursery area for North Sea cod, and that return migration to the North Sea are common (Svedäng et al., 2006). There are some indications that the proportion of recruits of North Sea origin has increased in recent years. The migration of this stock component out of the area at an older age could contribute to the estimate of unallocated removals in the latest years. Because of these uncertainties, the current level of fishing mortality cannot be reliably estimated. Concerning SSB, the estimates are considered imprecise, however both the assessment with and without estimating unallocated removals indicate historically lowest SSB in recent years (in the range of 1413 and 3406 tonnes in 2008). The level of SSB estimated from assessment is in line with the independent estimates of cod biomass based on data from the joint Swedish-Danish fishermen-scientist survey conducted in In benchmark assessment 2009, the estimates of SSB showed also to be robust for uncertainties concerning natural mortality and discards of young fish. The assessment cannot be used as a basis for forecast. Comparison with previous assessment and advice The overall perception of the state of the stock is unchanged compared to last year. Therefore, the advice is similar to last year, i.e. there should be no catch on this stock in Sources of information Report of the Baltic Fisheries Assessment Working Group. Copenhagen, April 2009 (ICES CM 2009/ACOM:07). Cardinale, M., and Svedäng, H Modelling recruitment and abundance of Atlantic cod, Gadus morhua, in the eastern Skagerrak Kattegat (North Sea): evidence of severe depletion due to a prolonged period of high fishing pressure. Fisheries Research, 69: Svedäng, H., Righton, D., and Jonsson, P Return migrations of Atlantic cod (Gadus morhua L.) to the North Sea evidenced by archival tagging of cod off the eastern Skagerrak coast. ICES CM 2006/Q:06. WKROUND Report of the Benchmark and Data Compilation Workshop for Roundfish January Copenhagen, Denmark (ICES CM 2009/ACOM:32) 14 ICES Advice 2009, Book 6

19 Table Cod in the Kattegat. Single stock exploitation boundaries (advice), management and landings. Year ICES Advice / 2005 onwards: Single-stock exploitation boundaries Predicted catch corresp. to advice Agreed TAC ICES landings 1987 Reduction in F < Reduction in F < TAC TAC TAC % reduction in fishing effort Limit fishing effort to 70% of 1991 effort Reduction in catch from < Precautionary TAC based on recent catches % Reduction in fishing effort from 1994 level Fishing effort should not exceed 70% of the 1994 level Fishing effort should not exceed 70% of the 1994 level F = At least 40% reduction in F F = Fpa = No fishery No fishery No fishery No fishery No fishery No fishery No catch No catch No catch 0 Weights in 000 t. 25,000 Landings (tonnes) 20,000 15,000 10,000 5, Figure Cod in the Kattegat: Reported landings in tonnes in ICES Advice 2009, Book 6 15

20 SSB Fbar Recruitment, Age 1 Figure Cod in the Kattegat. Mean SSB (t), Fbar and recruitment (Age 1, millions) from the runs with (black line) and without (red line) estimating unallocated removals. The latest estimate for SSB shown in the figure refers to the beginning of For Fbar and recruitment, the latest estimate is for Shaded area and broken lines represent 95% confidence intervals for the runs with and without estimating unallocated removals, respectively. Estimates of F in either runs are not considered reliable. Table Cod in the Kattegat. Estimated scaling factors for removals from the stock (average and 95% confidence intervals, indicated as Low and High) Year Catch multiplier Low High ICES Advice 2009, Book 6

21 Table Cod in the Kattegat. Reported landings (in tonnes) in Year Kattegat Denmark Sweden Germany 1 Total ,748 3, , ,451 3, , ,913 3, , ,043 4, , ,749 3, , ,986 3, , ,668 3, , ,293 2, , ,045 3, , ,265 4, , ,693 4, , ,320 3, , ,149 3, , ,590 4, , ,052 3, , ,930 2, , ,396 2, , ,054 1, , ,056 1, , ,715 1, , ,664 2, , ,406 2, , ,464 2, , ,968 2, , ,789 2, , ,028 2, , ,099 3, , ,207 2, , ,029 2, , ,285 1, , ,752 1, , , , , , , , Landings statistics incompletely split on the Kattegat and Skagerrak. 2 Including 900 t reported in Skagerrak. 3 Including t misreported by area. 4 Excluding 300 t taken in Sub-divisions Including 1.700t reported in Sub-division Including 116 t reported as pollack 7 the catch reported to the EU exceeds the catch reported to the WG (shown in the table) by 40% ICES Advice 2009, Book 6 17

22 Annex In December 2008 the European Council agreed on a new cod management plan implementing the new system of effort management and a target fishing mortality of 0.4 (EC 1342/2008). The HCR for setting TAC for the Kattegat cod stock are as follows: Article 6 The minimum spawning biomass level and the precautionary spawning biomass level for each of the cod stocks shall be as follows: Cod in the Kattegat Minimum spawning biomass Levels in tonnes Precautionary spawning biomass Levels in tonnes Article 7 Procedure for setting TACs for cod stocks in the Kattegat the west of Scotland and the Irish Sea 1. Each year, the Council shall decide on the TAC for the following year for each of the cod stocks in the Kattegat, the west of Scotland and the Irish Sea. The TAC shall be calculated by deducting the following quantities from the total removals of cod that are forecast by STECF as corresponding to the fishing mortality rates referred to in paragraphs 2 and 3: (a) a quantity of fish equivalent to the expected discards of cod from the stock concerned; (b) as appropriate a quantity corresponding to other sources of cod mortality caused by fishing to be fixed on the basis of a proposal from the Commission. 2. The TAC shall, based on the advice of STECF, satisfy all of the following conditions: (a) if the size of the stock on 1 January of the year of application of the TAC is predicted by STECF to be below the minimum spawning biomass level established in Article 6, the fishing mortality rate shall be reduced by 25 % in the year of application of the TAC as compared with the fishing mortality rate in the previous year; (b) if the size of the stock on 1 January of the year of application of the TAC is predicted by STECF to be below the precautionary spawning biomass level set out in Article 6 and above or equal to the minimum spawning biomass level established in Article 6, the fishing mortality rate shall be reduced by 15 % in the year of application of the TAC as compared with the fishing mortality rate in the previous year; and (c) if the size of the stock on 1 January of the year of application of the TAC is predicted by STECF to be above or equal to the precautionary spawning biomass level set out in Article 6, the fishing mortality rate shall be reduced by 10 % in the year of application of the TAC as compared with the fishing mortality rate in the previous year. 3. If the application of paragraph 2(b) and (c) would, based on the advice of STECF, result in a fishing mortality rate lower than the fishing mortality rate specified in Article 5(2), the Council shall set the TAC at a level resulting in a fishing mortality rate as specified in that Article. 4. When giving its advice in accordance with paragraphs 2 and 3, STECF shall assume that in the year prior to the year of application of the TAC the stock is fished with an adjustment in fishing mortality equal to the reduction in maximum allowable fishing effort that applies in that year. 5. Notwithstanding paragraph 2(a), (b) and (c) and paragraph 3, the Council shall not set the TAC at a level that is more than 20 % below or above the TAC established in the previous year. Article 9: Procedure for setting TACs in poor data conditions Where, due to lack of sufficiently accurate and representative information, STECF is not able to give advice allowing the Council to set the TACs in accordance with Articles 7 or 8, the Council shall decide as follows: (a) where STECF advises that the catches of cod should be reduced to the lowest possible level, the TACs shall be set according to a 25 % reduction compared to the TAC in the previous year; (b) in all other cases the TACs shall be set according to a 15 % reduction compared to the TAC in the previous year, unless STECF advises that this is not appropriate. 18 ICES Advice 2009, Book 6

23 Article 10: Adaptation of measures 1. When the target fishing mortality rate in Article 5(2) has been reached or in the event that STECF advises that this target, or the minimum and precautionary spawning biomass levels in Article 6 or the levels of fishing mortality rates given in Article 7(2) are no longer appropriate in order to maintain a low risk of stock depletion and a maximum sustainable yield, the Council shall decide on new values for these levels. 2. In the event that STECF advises that any of the cod stocks is failing to recover properly, the Council shall take a decision which: (a) sets the TAC for the relevant stock at a level lower than that provided for in Articles 7, 8 and 9; (b) sets the maximum allowable fishing effort at a level lower than that provided for in Article 12; (c) establishes associated conditions as appropriate. ICES Advice 2009, Book 6 19

24 6.4.2 Cod in Subarea IV (North Sea), Division VIId (Eastern Channel), and IIIa West (Skagerrak) State of the stock Spawning biomass in relation to precautionary limits Reduced reproductive capacity Fishing mortality in relation to precautionary limits Fishing mortality in relation to high longterm yield Fishing mortality in relation to agreed target Increased risk Overfished Above target Comment Based on the most recent estimate of SSB (in 2009) and fishing mortality (in 2008), ICES classifies the stock as suffering reduced reproductive capacity and as being at risk of being harvested unsustainably. SSB has increased since its historical low in 2006, but remains below B lim. Fishing mortality declined after 2000, but in 2008 increased, predominantly as a consequence of increased discarding and is currently estimated to be between F lim and F pa. The 2005 year class is estimated to be one of the most abundant amongst the recent below-average year classes. The 2008 year class is estimated to be one of the lowest in the series. Management objectives The EU Norway agreement management plan as updated in December 2008 aims to be consistent with the precautionary approach and is intended to provide for sustainable fisheries and high yield leading to a target fishing mortality to 0.4. (for details see Annex 6.4.2). The EU has adopted a long-term plan for this stock with the same aims (Council Regulation (EC) 1342/2008). ICES has evaluated the management plan in 2009 and considers it to be in accordance with the precautionary approach if it is implemented and enforced adequately. Discarding in excess of the assumptions under the management plan will affect the effectiveness of the plan. The evaluation is most sensitive to assumptions about implementation error (i.e. TAC and effort overshoot and the consequent increase in discards). Reference points Type Value Technical basis Precautionary approach B lim t Bloss (~1995) B pa t Bpa = Previous MBAL and signs of impaired recruitment below t. F lim 0.86 Flim = Floss (~1995) F pa 0.65 Fpa = Approx. 5th percentile of Floss, implying an equilibrium biomass > Bpa. Targets F mgt 0.4 EU/Norway agreement and EU management plan 1342/08 (Unchanged since 1998, management plan target added in 2008) Yield and spawning biomass per Recruit F-reference points (2009): Fishing Mortality Yield/R SSB/R Ages 2-4 Average last 3 years 0.79 F max F F med Estimated by ICES in 2009, assuming constant maturity, with M and stock weights averaged over the period Selectivity is averaged over ICES Advice 2009, Book 6

25 In 2005, ICES advised that, on the basis of evaluations of harvest control rules for North Sea cod, target fishing mortalities (covering all catches) below 0.4 (ages 2 4) would result in a low risk of SSB falling below the conservation limit B lim and would achieve high long-term yields Single-stock exploitation boundaries Considering the options below, ICES advises on the basis of the management plan on an F in 2010 that is 65% of the F in 2008 (F2010=0.51), catches should be less t. Assuming discards rates as observed in 2008, this implies landings of less than t in This presumes that the objectives of the management plan are realised which assumes reduction in F and control of catches in 2009 and Exploitation boundaries in relation to existing management plans The plan stipulates that, based on the assumption that the 25% reduction in F in 2009 has been effective in reducing F 2009 to 25% below F 2008, the following criteria be met, in order of increasing priority: (a) TAC 2009 should not exceed a level that results in F 2010 being above 65% of F 2008 ; (b) There should be no more than a 20% change from TAC 2009 to TAC 2010 ; These criteria imply catches should be less t. Assuming discards rates as observed in 2008, this implies landings of less than t in 2010.This is less than the 20% increase constraint (1.2 TAC 2009 = t) for Area IV and Subdivisions VIId and IIIa (Skagerrak). Exploitation boundaries in relation to high long-term yield, low risk of depletion of production potential and considering ecosystem effects F 2008 is above the levels that would lead to high long-term yield and low risk of depletion of production potential, taking ecosystem effects into account. Exploitation boundaries in relation to precautionary limits Given the low stock size and recent poor recruitment, the stock cannot be rebuilt to B pa at the start of 2011 even with a zero catch. Simulations indicate that with the recent poor recruitment, a zero catch in 2010 and 2011 is likely to achieve the rebuilding of the stock to B pa by ICES Advice 2009, Book 6 21

26 22 ICES Advice 2009, Book 6 Short-term implications Outlook for 2010 Management plan assumptions Basis; F 09 = [management plan] = 0.75F 08 = 0.59 (land=0.29, disc=0.30); R = (re-sampled from YC, median of YC) ~110 million; SSB(2010) = 66.0; Landings (2009) = 41.9; Discards (2009) = Rationale Catches (2010) Landings (2010) Basis F total (2010) F land (2010) F disc (2010) Discards (2010) SSB (2011) %SSB change 1) %TAC change 2) Management F 10 = % 17% Plan 0.65*F 08 This option is considered precautionary in the context of the long term management plan. ICES assumptions Basis: F sq = F scaled to F 08 = 0.79; R = (re-sampled from YC, median of YC) ~110 million; SSB(2010) = 54.2; Landings (2009) = 51.5; Discards (2009) = Rationale Catches (2010) Landings (2010) Basis F total (2010) F land (2010) F disc (2010) Discards (2010) SSB (2011) %SSB change 1) %TAC change 2) Zero Catch F= % -100% *Fsq % -19% *Fsq % -13% *Fsq % -7% *Fsq % -1% Status quo *Fsq % 5% options *Fsq % 10% *Fsq % 15% *Fsq % 21% *Fsq % 26% Fsq % 35% Weights in 000 t. Shaded areas are not considered consistent with the precautionary approach in the short term. 1) SSB 2011 relative to SSB ) Landings 2010 relative to TAC 2009 (Total = t for the Skagerrak; VIId and IV; EC waters of IIa; that part of IIIa not covered by the Skagerrak and Kattegat) 22 ICES Advice 2009, Book 6

27 Management considerations The 2008 advice from ICES for this stock was a zero catch in 2009 because it did not consider the former recovery plan precautionary. The ICES advice for 2010 indicates that catches of cod can be allowed under the new management agreement. This change in advice is because the new management agreement is considered to be consistent with the precautionary approach. It should be emphasised that the new agreement is only consistent with the precautionary approach if it is implemented and enforced adequately. ICES has observed that there have been considerable problems with the effectiveness of the former recovery plan. Despite the objective of the plan to reduce fishing mortality and to increase the SSB by combined TAC control and effort management, estimated catches have been much higher than intended in the management plan. Although fishing mortality has been reduced after 2000, it has remained well above the targets implied by the plan and has increased again in Also discarding increased in 2007 and 2008 and contributed about half of the total fishing mortality in these years. Under the present implementation and enforcement approach, reduction in F and the recovery of the stock is unlikely under either management plan. It is therefore urgent to make significant improvements in implementation and enforcement to achieve reduction in F by effective control of cod catches. In recent years surveys indicate that the year classes are depleting faster than one would expect from the catches and point to unaccounted removals. There is no documented information on the source of these unaccounted removals; while it is assumed that these removals originate mostly from fishing activities, changes in natural mortality may also have an influence. Plausible fishery-based contributions to these unaccounted removals are discards that do not count against quota, and the mis- and under-reporting of catches (although the latter are considered to have reduced in recent years following changes to national reporting procedures). The recorded landings from have fluctuated between 30% and 55% of the total removals. This indicates that the management system has not been effective in controlling the catches. Although the absolute levels of current SSB and fishing mortality are considered uncertain (Figure ), fishing mortality rates have been reduced after 2000 and, due to the 2005 year class, the stock has increased since However, all recent year classes have been poor. The low average age of the spawning stock reduces its reproductive capacity, as first-time spawners reproduce less successfully than older fish which is considered to be a factor that has contributed to the continued low recruitment. In 2008, 94% of 1 year old, 73% of 2 year old, 64% of 3 year old (the abundant 2005 year class) and 12% of 4 year old cod (in numbers) were discarded. This resulted in discard mortality which exceeded landings mortality (Figure and Figure ). The recruitment of the relatively more numerous 2005 year-class to the fishery will have no beneficial effect on the current spawning biomass if it continues to be caught and heavily discarded. ICES notes that there have been considerable efforts to reduce discards by some countries, but it is too premature to evaluate the impact these have had in reducing discard mortality. It is important that the effectiveness of the existing measures is monitored and if discarding is still considered to be too high, then additional technical, temporal or spatial measures should be promptly introduced that are effective in reducing discards. The 2006 year class is locally abundant in the southern North Sea and Eastern Channel. This is causing high rates of discards and high-grading in 2008 and 2009 in the Eastern Channel. The 2006 year class is estimated as high as the 1996 year class in the Eastern Channel by the French ground fish survey but was found to be poor in the North Sea, based on the IBTS Q1 and Q3 surveys. Several nations, who make substantial landings of cod, have not supplied ICES with estimates of discards that can be used within the assessment process, despite the requirement to do so according to EU data collection regulations. In order to improve the quality of the assessment, and hence management advice, these nations should be encouraged to do so. Cod are taken by towed gears in mixed demersal fisheries, which include haddock, whiting, Nephrops, plaice, and sole. They are also taken in directed fisheries using fixed gears. For management to be effective, both species-specific assessments and the latest developments in mixed fisheries approaches need to be considered. A reduction in direct effort on one stock may lead to a reduction or an increase in effort on another and, hence, the implications of any changes need to be identified and carefully evaluated. Cod catch in Division VIId was managed by a TAC for Divisions VIIb-k,VIII, IX, X, and CECAF , (i.e. the TAC covers a small proportion of the North Sea cod stock together with cod in Divisions VIIe-k). Division VIId was allocated a separate TAC for 2009 which was adjusted in line with the revision to the North Sea TAC. ICES has developed a generic approach to evaluate whether new survey information that becomes available in September forms a basis to update the advice. If this is the case, ICES will publish new advice in November ICES Advice 2009, Book 6 23

28 Management plan evaluations In December 2008 the European Commission and Norway agreed on a new cod management plan implementing a new system of linked effort management with a target fishing mortality of 0.4 (EC 1342/2008 and Annex 6.4.2). ICES has evaluated the EC management plan in March 2009 and concluded that this management plan is in accordance with the precautionary approach only if implemented and enforced adequately. During the evaluation, ICES assumed that the annual effort reduction is fully achieved and the target F is achieved. Recovery is sensitive to assumptions about implementation error (i.e. scenarios of TAC and effort overshoot and increase in discards) and a continuation of the current low recruitment. Under these scenarios recovery to a precautionary status is delayed until after the required target date of The application of the 20% TAC constraint results in reductions in fishing mortality to values that are so low (e.g. F = 0.1 by ~ 2012) that it is impractical for effort to be reduced to the levels required, possibly even for by-catch fisheries. At such low levels of fishing, the behaviour of the mixed fishery is considered highly uncertain and the management plan evaluation assumptions will break down, especially with respect to discard practices. Removing the TAC constraint might reduce the level of discards and lead to more appropriate management and fishing practices but would also delay the recovery. Impacts of fisheries on the ecosystems Cod is targeted by a gillnet fishery, primarily conducted by Denmark and the UK, with a substantial bycatch of harbour porpoise. In 2001 the total bycatch in the cod fishery was around 2000 porpoises. Since 2001, effort reductions in this fishery have likely led to decreased bycatches of porpoises. The effect on the benthic invertebrate community in the northern North Sea from all otter trawling is estimated to represent an annual mortality of approximately 25% of the standing-crop biomass. The MAFCONS and STECF data set suggest that otter trawl effort directed at fish has declined since 1999 (Greenstreet et al., 2007). Factors affecting the fisheries and the stock Regulations and their effects Spatial management has been attempted for cod, both in the form of a closure of a large area of the North Sea in 2001 (Council Regulation (EC) 259/2001) and through implementation of a cod protection area in 2004 (EC 2287/2003). None of these measures appeared to have had the desired effect and both were abandoned shortly after implementation. In 2001, cod in the whole of NEAFC region 2 was a legitimate target species for towed gears with a minimum codend mesh size of 100 mm. As part of the cod recovery measures, the EU and Norway introduced additional technical measures from 1 January 2002 (EC 2056/2001). The basic minimum mesh size for towed gears for cod, apart from some transitional arrangements, has been 120 mm from This resulted in a shift in effort towards smaller meshed fisheries. Effort restrictions in the EC were introduced in 2003 (annual annexes to the TAC regulations) for the protection of the North Sea (?) cod stock. In 2009, the management program switched from a days at sea to a kw/day system (2009 Council Regulation (EC) N 43/2009), in which different amounts of kw/days are allocated within each area by Member State to different groups of vessels depending on gear and mesh size. In 2008, STECF indicated that overall effort (kw/days) by demersal trawls, seines and beam trawls had been substantially reduced since Fishing mortality declined between 2003 and 2007 concomitant with this effort reduction, but F increased again in 2008 despite a further nominal reduction in effort. Marked changes have also occurred in the use of the different mesh size categories by demersal trawlers. A sharp reduction has occurred in the use of mesh sizes between 100mm and 119mm, while a pronounced increase is apparent in the use of mesh sizes of 120mm and greater. As well, a general increase in effort has been observed in vessels using mesh sizes of 70-89mm and 90-99mm. Scotland implemented in February 2008 a national scheme known as the Conservation Credits Scheme. The principle of this two-part scheme involves additional time at sea in return for the adoption of measures which aims to reduce mortality on cod and lead to a reduction in discard numbers. ICES has not yet been able to evaluate the consequences of these measures. Despite their introduction, ICES notes that during the initial year of operation (2008) cod discarding rates increased substantially. A new rights-based regulation (FKA Vessel Quota Share) was put in force in Denmark from the 1st January With the new system, individual vessels are allocated a yearly share of the Danish quota, which can be taken at any time 24 ICES Advice 2009, Book 6

29 of the year. There is also a possibility to trade it, exchange it, or pool it with other fishers. The old regulation had a system with 14-day quotas, which continuously adjusted to the amount of national quota left. The new system gives the industry a possibility to plan better and is expected to lead to a more efficient fishery with less discards. ICES has not yet been able to evaluate the consequences of these measures. Changes in fishing technology and fishing patterns WGFTFB (ICES, 2009) note that the decline in fuel costs from 2008 to 2009 have influenced the operational dynamics of some fleets that traditionally target mixed demersal species in the North Sea by lowering the costs associated with fishing in more distant areas. This has been further enhanced by the introduction of a more restrictive effort regime in IV, VIId and VIa and the absence of effort restrictions in other areas. These factors are thought to have contributed to a shift in effort away from IV towards fisheries in Rockall, the Celtic Sea and the Porcupine. The extent of the effort transfer cannot currently be quantified, but is likely to be significant and fishing patterns in 2009 may be very different to those observed in The expected benefits from the increase in mesh size to 120 mm are not apparent from the available data. The effect of this increase is confounded by the transfer of effort from the fleets fishing with mesh sizes >120 mm to fleets fishing with mesh sizes between 70 and 99 mm, i.e. fishing for Nephrops. The regulation differentiated between the number of fishing days allowed when fishing for Nephrops or when fishing for other demersal species (>120 mm). Fishing for Nephrops with the smaller mesh allowed more days at sea than fishing with larger meshes. The introduction of the one-net rule as part of the Scottish Conservation Credit Scheme is likely to improve the accuracy of reporting of metier-based landings. Scottish legislation implemented in January 2008, banning the use of multi-rigs (>2 rigs per trawl), could limit the potential of uncontrolled increase in effort. There has also been a move in Scottish vessels from using mm for whitefish on west coast ground (Subarea VI) to the North Sea using 80 mm prawn codends, which could imply increased discarding. A move from the Farn Deeps Nephrops fishery into other fisheries for whitefish because of poor Nephrops catch rates, implies increased effort in whitefish fisheries. Impacts of the environment on the fish stock The North Sea has seen a northerly shift in the mean latitudinal distribution of the stock. However, the evidence for this in the form of a migratory response is slight or non-existent. More likely, cod in the North Sea are composed of a complex of more or less isolated sub-stocks and the southern units have been subjected to disproportionately high rates of fishing mortality. The contracted range of the North Sea cod stock can be linked to reduced abundance as well as climate factors. The consumption of cod in the North Sea in 2002 by grey seals has recently been estimated (Hammond and Grellier, 2006). For the North Sea it was estimated that in 1985 grey seals consumed 4150 tonnes of cod (95% confidence intervals; tonnes), and in 2002 the population tripled in size ( individuals) and consumed 8344 tonnes (95% confidence intervals; tonnes). Inclusion of the new grey seal diet data and seal population abundance are expected to reduce slightly the historic estimates of cod consumption in the North Sea by seals, generated from a multispecies model previously used. This suggests that the new estimates of seal predation will not alter the current perception of North Sea cod stock dynamics. Scientific basis Data and methods The age-based assessment model (B-ADAPT) used landings and discards, calibrated with two survey indices (from IBTS quarter 1 and quarter 3 surveys). For ICES Subarea IV and Division VIId, discards were estimated from the Scottish discards sampling programme up until 2005 and raised to the total international fleet. For 2006 Denmark provided its own discard estimates. For 2007 and 2008 Scottish, Danish, German, and England and Wales discard estimates were combined and used to raise landings-at-age for remaining nations in Subarea IV. Discards in Division IIIa were based on observer estimates. For , Danish and Swedish discard estimates were combined to raise landings-at-age from the remaining nations in Division IIIa. The assessment and forecast made use of the 2009 Quarter 1 IBTS survey. Because of unreliable information on landings and effort, commercial indices were not used in the assessment. Instead, the assessment uses only survey data for calibration. The natural mortality values used in the assessment have been revised based on new estimates from the multi-species model. Quantities of additional unallocated removals were estimated by the model on the basis of the total mortality indicated by the survey. In addition to the B-ADAPT model a new model (state space SAM model) was used ICES Advice 2009, Book 6 25

30 to validate the estimates of unallocated removals. Both models gave similar estimates of SSB and total F although there were differences in unallocated removals. The unallocated removals estimates could potentially include components associated to increased natural mortality and discarding as well as unreported landings. It is, however, assumed that all of these removals originate from fishing activities. A series of medium-term projections were used to evaluate management scenarios. The catch options in the forecast table represent median values from the projections. All scenarios assume a 25% reduction in fishing mortality in 2009 to account for a 25% reduction in effort for the main cod gears, as stipulated in EC 1342/2008. Landings and discards in the forecast are estimated by applying the landing- and discard-at-age ratios for 2008 to total fishing mortality-at-age for the projection period. Figures a and b illustrate two scenarios, one with constant fishing at the 2009 level (Figures a) and the other a closure from 2010 onwards (Figures b). The closure option is expected to bring SSB above B lim in 2012 with 95% probability. Information from the fishing industry Comparison between the fishers North Sea Stock Survey and the IBTS survey data has been shown in previous years the time series are broadly in agreement in recording a stable overall stock abundance until followed by an increase more recently, especially in the north-western North Sea. The IBTS surveys have more variability, due to the inherent spatial variation, but exhibit similar trends in the same areas as the fishers survey, with significant increases in the north and west. In May 2008, French fishers targeting cuttlefish in the eastern Channel reported discards of several tonnes per haul of undersized cod in ICES rectangle 28F0, forcing them to leave their usual cuttlefish fishing area. They reported that this also occurred in Data collected in the Channel by French fishers and submitted to the ICES WGNSSK in 2009 indicate high rates of discards for lengths between 37 and 48cm (ages 2 and 3), confirming the information from previous years and indicate recent improved recruitment and survivorship in the southern North Sea and VIId. Uncertainties in assessment and forecast A large part (approximately 50% in 2007 and 2008) of the total catch used in the assessment is discards estimated from relatively low sample numbers compared to landings, and through estimation of unallocated mortality rates. Raised discard information was not available for a major component of the catch in the southern part of the North Sea and in the eastern Channel from French fleets. These are sources of added uncertainty in the assessment. Comparison with previous assessment and advice: The fishing mortality for 2007 has been revised downwards by 3% compared to the last assessment (May 2008) while SSB in 2008 was revised upwards by 15%. The F 2008 estimate, at 0.79 is a 36% increase on the F 2008 (0.58) used for the previous years' forecast, which was based on the 10% reduction in fishing effort in 2008 imposed in that year. The natural mortality values used in the assessment have been revised based on new estimates from the multi-species model.. The basis for the advice has changed from precautionary limits to the management plan since this was evaluated in 2009 and found to be consistent with the precautionary approach when implemented and enforced adequately. Sources of information Report of the Working Group on the Assessment of Demersal Stocks in the North Sea and Skagerrak, 6-12 May 2009 (ICES CM 2009/ACOM:10). Greenstreet, S., Robinson, L., Piet, G., Craeymeersch, J., Callaway, R., Reiss, H., Ehrich, S., Kröncke, I., Fraser, H., Lancaster, J., Jørgensen, L., and Goffin, A The ecological disturbance caused by fishing in the North Sea. Fisheries Research Services, Aberdeen, U.K. Collaborative Report No. 04/07, 169 pp. Grellier, K., and Hammond, P. S Robust digestion and passage rate estimates for hard parts of grey seal (Halichoerus grypus) prey. Canadian Journal of Fisheries and Aquatic Sciences, 63: ICES 2009, ICES FAO Working Group on Fishing Technology and Fish Behaviour [WGFTFB], (ICES CM 2009/ FTC:06). STECF PLEN EUR EN, ISBN , ISSN , DOI /3484, ICES Advice 2009, Book 6

31 ICES Advice 2009, Book 6 27 Table North Sea (Subarea IV) Year ICES Advice Cod in Subarea IV (North Sea), Division VIId (Eastern Channel), and Division IIIa (Skagerrak). Single-stock exploitation boundaries (advice), management, and catch/landings. Landings for each of the three parts of this combined-area assessment, and for all areas combined are given in Table Single-stock exploitation boundaries Predicted catch corresponding to advice Predicted catch corresp. to singlestock exploitation boundaries ICES Advice 2009, Book 6 27 Agreed TAC Official landings 1987 SSB recovery; TAC % of F(86); TAC Halt SSB decline; protect juveniles; TAC % of F (88); TAC % of effort (89) % of effort (89) % of effort (89) Significant effort reduction Significant effort reduction % of F(94) = % of F(95) = F(98) should not exceed F(96) F = 0.60 to rebuild SSB F less than 0.55 < lowest possible catch lowest possible catch Closure NA 2004 Zero catch Zero catch NA 2005 Zero catch Zero catch NA 2006 Zero catch Zero catch NA 2007 Zero catch Zero catch NA 2008 Exploitation boundaries in relation to precautionary limits Total removals < t 2009 Zero catch Zero catch Management plan F (65% of F2008) < ) Weights in 000 t. 1) For Subarea IV (North Sea), Division VIId (Eastern Channel), and Division IIIa (Skagerrak) < 22 < NA ICES landings

32 28 ICES Advice 2009, Book 6 Skagerrak (Division IIIa) Year ICES Advice 28 Single-stock exploitation boundaries Predicted catch corresponding to advice Predicted catch corresp. to singlestock exploitation boundaries Agreed TAC 1 Official landings 1987 F = F max < Reduce F F at F med < F at F med ; TAC TAC % of F(90) Precautionary TAC No long-term gain in increased F + precautionary TAC If required precautionary TAC; link to North Sea If required precautionary TAC; link to North Sea If required precautionary TAC; link to North Sea If required precautionary TAC; link to North Sea F = 0.60 to rebuild SSB F less than 0.55 < lowest possible catch lowest possible catch Closure NA 2004 Zero catch Zero catch NA 2005 Zero catch Zero catch NA 2006 Zero catch Zero catch NA 2007 Zero catch Zero catch NA 2008 Exploitation boundaries in relation to precautionary limits Total removals less than < 22 < NA t 2009 Zero catch Zero catch Management plan F (65% of F2008) < ) Weights in 000 t. 1) Norwegian fjords not included. 2) For Subarea IV (North Sea), Division VIId (Eastern Channel), and Division IIIa (Skagerrak) ICES landings 1 ICES Advice 2009, Book 6

33 ICES Advice 2009, Book 6 29 Eastern Channel (Division VIId) Year ICES Advice Single-stock exploitation boundaries Predicted catch corresponding to advice Predicted catch corresp. to singlestock exploitation boundaries ICES Advice 2009, Book 6 29 Agreed TAC 1) Official landings 1987 Not assessed Precautionary TAC No increase in F; TAC ) - n/a No increase in F; TAC 9.0 2) - n/a Precautionary TAC 3.0 2) - n/a If required, precautionary TAC 5.5 2) If TAC required, consider SSB decline Reduce F+ precautionary TAC Significant effort reduction; link to North Sea Reference made to North Sea advice No advice Link to North Sea F = 0.60 to rebuild SSB n/a F less than 0.55 < lowest possible catch lowest possible catch Closure NA 2004 Zero catch Zero catch NA 2005 Zero catch Zero catch NA 2006 Zero catch Zero catch NA 2007 Zero catch Zero catch NA 2008 Exploitation boundaries in relation to precautionary limits Total removals less than t < 22 < NA 2009 Zero catch Zero catch Management plan F (65% of F2008) < ) Weights in 000 t. 1) Until 2008 this area was included in TAC for Subarea VII (except Division VIIa), from 2009 a separate TAC is set. 2) Including Division VIIe. 3) For Subarea IV (North Sea), Division VIId (Eastern Channel), and Division IIIa (Skagerrak) ICES landings

34 SSB 1.4 F(2-4) TSB Catch R (age 1) Catch multiplier Figure Cod in Subarea IV (North Sea), Division VIId (Eastern Channel), and Division IIIa (Skagerrak). Clockwise from top left: percentiles (5,25,50,75,95) of the estimated spawning-stock biomass (SSB), total stock biomass (TSB), recruitment (R(age 1)), and the catch multiplier, catch, and mean fishing mortality for ages 2 4 (F(2 4)) from the B-ADAPT base run. The heavy lines represent the bootstrap median, the light broken lines the 25th and 75th percentiles, and the heavy broken lines the 5th and 95th percentiles. The solid diamonds represent point estimates, and the open diamonds given in the catch plot the recorded total catch. The horizontal broken lines in the SSB plot indicate B lim = t and B pa = t, and those in the F(2 4) plot F pa = 0.65 and F lim = The horizontal solid line in the catch multiplier plot indicates a multiplier of 1. Catch, SSB, and TSB are in tonnes, R is in thousands. 30 ICES Advice 2009, Book 6

35 1.6 F(2-4) 1.2 landings discards Discards Landings F (2-4) Figure Cod in Subarea IV, Divisions IIIa (Skagerrak) and VIId. The mean fishing mortality for ages 2-4 separated into landings and discards components by using ratios calculated from the landings and discards numbers at age from the reported catch data. The top panel shows bootstrap medians (heavy lines) with 25th and 75th percentiles (light broken lines), and 5th and 95th percentiles (heavy broken lines), while the bottom panel shows a stacked-area plot of the bootstrap medians. ICES Advice 2009, Book 6 31

36 1 Proportion discarded at age (by number) age age age 3 age Figure Cod in Subarea IV and Divisions IIIa (Skagerrak) and VIId: Proportion of total numbers caught at age that are discarded. In 2008, 94% of 1 year old, 73% of 2 year old, 64% of 3 year old (the abundant 2005 year class) and 12% of 4 year old cod, were discarded. 32 ICES Advice 2009, Book 6

37 Constant F Fbar(2-4) Catch/Removals (Tonnes) SSB Recruitment Closure Fbar(2-4) Catch/Removals (Tonnes) SSB Recruitment Figure a Cod in Subarea IV (North Sea), Division VIId (Eastern Channel), and Division IIIa (Skagerrak). B-ADAPT forecast for a reduction in fishing mortality by 25% from 2009, followed by Top 4 graphs; constant fishing mortality at the 2009 level for 2010 onwards. Bottom 4 graphs; a closure of the fishery for 2009 onwards. Broken lines represent bootstrap percentiles (5,25,75,95), and the solid trajectory the median. ICES Advice 2009, Book 6 33

38 Stock - Recruitment Recruitment (age 1) in billions SSB in 1000 t SSB-Rec. Blim Bpa Precautionary Approach Plot Period SSB in 1000 t Fishing Mortality (ages 2-4) F-SSB 2008 Flim Fpa Blim Bpa Figure Cod in Subarea IV (North Sea), Division VIId (Eastern Channel), and Division IIIa (Skagerrak). Spawning stock recruitment and precautionary approach plot. 34 ICES Advice 2009, Book 6

39 Figure Cod in Subarea IV (North Sea), Division VIId (Eastern Channel), and Division IIIa (Skagerrak). Results of the North Sea Commission fishers survey SSB ('000 tonnes) Fishing mortality: Millions Recruitment. Age: Figure Cod in Subarea IV (North Sea), Division VIId (Eastern Channel), and Division IIIa (Skagerrak). Historical performance of the assessment. ICES Advice 2009, Book 6 35

40 Table Cod in Subarea IV (North Sea), Division VIId (Eastern Channel), and Division IIIa (Skagerrak). Nominal landings (in tonnes) of COD, , as officially reported to ICES, and as used by the Working Group. Sub-area IV Country Belgium 3,398 2,934 2,331 3,356 3,374 2,648 4,827 3,458 4,642 5,799 Denmark 25,782 21,601 18,997 18,479 19,547 19,243 24,067 23,573 21,870 23,002 Faroe Islands France 2,578 1, ,146 1,868 1,868 3,040 1,934 3,451 2,934 Germany 11,430 11,725 7,278 8,446 6,800 5,974 9,457 8,344 5,179 8,045 Greenland Netherlands 12,028 8,441 6,831 11,133 10,220 6,512 11,199 9,271 11,807 14,676 Norway 4,813 5,168 6,022 10,476 8,742 7,707 7,111 5,869 5,814 5,823 Poland Sweden UK (E/W/NI) 18,035 15,593 14,249 14,462 14,940 13,941 14,991 15,930 13,413 17,745 UK (Scotland) 31,828 31,187 29,060 28,677 28,197 28,854 35,848 35,349 32,344 35,633 Total Nominal Catch 110,452 99,059 86,565 98,107 94,380 87, , ,407 99, ,324 Unallocated landings 5,248 5,692 1, ,200 7,066 8,555 2,161 2,746 7,779 WG estimate of total landings 115, ,751 88,533 97, ,580 94, , , , ,103 Agreed TAC 124, , , , , , , , , ,000 Division VIId Country Belgium Denmark < France... 2,079 1,771 2,338 3,261 2,808 6,387 7,788 Netherlands UK (E/W/NI) UK (Scotland) <0.5 < Total Nominal Catch ,734 2,460 2,887 3,974 3,547 7,178 8,665 Unallocated landings 4,801 2,097 1, WG estimate of total landings 5,538 2,763 1,886 2,669 2,432 2,850 3,964 3,503 7,043 8,580 Division IIIa (Skagerrak)** Country Denmark 16,634 15,819 10,294 11,187 11,994 11,921 15,888 14,573 12,159 12,339 Germany Norway 1,003 1, ,208 1, ,039 1,046 1,323 1,293 Sweden 1,805 1,136 3,846 2,523 2,575 1,834 2,483 1,986 2,173 1,900 Others Norwegian coast * Danish industrial by-catch * , Total Nominal Catch 19,476 18,150 15,105 15,020 16,230 15,075 19,829 17,864 15,736 15,586 Unallocated landings ,046-1,018-1,493-1,814-7,720-1, WG estimate of total landings 18,697 17,800 12,059 14,002 14,737 13,261 12,109 16,249 14,946 15,331 Agreed TAC 20,500 21,000 15,000 15,000 15,000 15,500 20,000 23,000 16,100 20,000 Sub-area IV, Divisions VIId and IIIa (Skagerrak) combined Total Nominal Catch 130, , , , , , , , , ,575 Unallocated landings 9,271 7, ,841 8,679 5, ,821 7,439 WG estimate of total landings 139, , , , , , , , , ,014 ** Skaggerak/Kattegat split derived from national statistics * The Danish industrial by-catch and the Norwegian coast catches are not included in the (WG estimate of) total landings of Division IIIa. Magnitude not available - Magnitude known to be nil <0.5 Magnitude less than half the unit used in the table n/a Not applicable Division IIIa (Skagerrak) landings not included in the assessment Country Norwegian coast * Danish industrial by-catch * , Total 1,316 1,533 1,807 2,283 1,420 1,426 1,595 1,424 1,116 1, ICES Advice 2009, Book 6

41 Table cont Cod in Subarea IV (North Sea), Division VIId (Eastern Channel), and Division IIIa (Skagerrak). Nominal landings (in tonnes) of COD, , as officially reported to ICES, and as used by the Working Group. Sub-area IV Country Belgium 3,882 3,304 2,470 2,616 1,482 1,627 1,722 1,309 1, Denmark 19,697 14,000 8,358 9,022 4,676 5,889 6,291 5,105 3,430 3,828 Faroe Islands France. 1, , Germany 3,386 1,740 1,810 2,018 2,048 2,213 2,648 2,537 1,899 1,736 Greenland Netherlands 9,068 5,995 3,574 4,707 2,305 1,726 1,660 1,585 1,523 1,896 Norway 7,432 6,410 4,369 5,217 4,417 3,223 2,900 2,749 3,057 4,128 Poland Sweden UK (E/W/NI) 10,344 6,543 4,087 3,112 2,213 1,890 1,270 1,491 1,587 n/a UK (Scotland) 23,017 21,009 15,640 15,416 7,852 6,650 4,936 6,857 6,511 n/a UK (combined) n/a n/a n/a n/a n/a n/a n/a n/a n/a 8,727 Others Norwegian indust by-catch * Danish industrial by-catch * Total Nominal Catch 77,566 60,881 41,713 44,421 25,936 23,789 22,479 23,108 20,063 22,272 Unallocated landings 826-1, , WG estimate of total landings 78,392 59,767 40,973 44,300 25,847 23,549 23,870 22,193 19,683 22,195 Agreed TAC 132,400 81,000 48,600 49,300 27,300 27,300 27,300 23,205 19,957 22,152 Division VIId Country Belgium Denmark France. 3,084 1,677 1,361 1, ,124 1, Netherlands UK (E/W/NI) n/a UK (Scotland) n/a UK (conbined) n/a n/a n/a n/a n/a n/a n/a n/a n/a 151 Total Nominal Catch 629 3,583 2,036 1,563 1, ,230 1,485 2,065 1,096 Unallocated landings 6,229-1, , WG estimate of total landings 6,858 2,325 1,573 3,097 1, ,033 1,127 1,740 1,354 Division IIIa (Skagerrak)** Country Denmark 8,682 7,656 5,870 5,511 3,054 3,009 2,984 2,478 2,228 2,534 Germany Norway 1, Sweden 1,909 1,293 1, Others Norwegian coast * Danish industrial by-catch * Total Nominal Catch 11,791 9,929 7,699 7,136 4,465 4,483 4,338 3,935 3,731 3,743 Unallocated landings WG estimate of total landings 10,974 9,277 7,086 7,468 3,791 3,787 3,805 3,366 2,946 3,298 Agreed TAC 19,000 11,600 7,000 7,100 3,900 3,900 3,900 3,315 2,851 3,165 Sub-area IV, Divisions VIId and IIIa (Skagerrak) combined Total Nominal Catch 89,986 74,393 51,448 53,120 32,342 29,246 28,047 28,528 25,859 27,112 Unallocated landings 6,239-3,024-1,816 1,745-1,470-1, ,842-1, WG estimate of total landings 96,225 71,369 49,632 54,865 30,872 28,143 28,708 26,686 24,369 26,847 ** Skaggerak/Kattegat split derived from national statistics * The Danish and Norwegian industrial by-catch and the Norwegian coast catches are not included in the (WG estimate of) total landings. Magnitude not available - Magnitude known to be nil <0.5 Magnitude less than half the unit used in the table n/a Not applicable Division IV and IIIa (Skagerrak) landings not included in the assessment Country Norwegian coast * Norwegian indust by-catch * Danish industrial by-catch * Total , ICES Advice 2009, Book 6 37

42 Table Cod in Subarea IV (North Sea), Division VIId (Eastern Channel), and Division IIIa (Skagerrak). Landings, discards, and estimated total removals in tonnes. Landings Discards Catch (L+D) Total estimated removals ICES Advice 2009, Book 6

43 Table Cod in Subarea IV (North Sea), Division VIId (Eastern Channel), and Division IIIa (Skagerrak). Summary from stock assessment. Run title: North Sea/Skagerrak/Eastern Channel Cod Tuning data. INCLUDES DISCARDS 30/04/ :26 B-ADAPT median values RECRUITS TSB SSB CATCH YIELD/SSB FBAR 2-4 Age 1 ('000) (tons) (tons) (tons) ICES Advice 2009, Book 6 39

44 Annex EU Norway management plan In 2008 the EU and Norway renewed their initial agreement from 2004 and agreed to implement a long-term management plan for the cod stock, which is consistent with the precautionary approach and is intended to provide for sustainable fisheries and high yield. Transitional arrangement: F will be reduced as follows: 75 % of F in 2008 for the TACs in 2009, 65 % of F in 2008 for the TACs in 2010, and applying successive decrements of 10 % for the following years. The transitional phase ends as from the first year in which the long-term management arrangement (paragraphs 3 5) leads to a higher TAC than the transitional arrangement. Long-term management 1. If the size of the stock on 1 January of the year prior to the year of application of the TACs is: a. Above the precautionary spawning biomass level, the TACs shall correspond to a fishing mortality rate of 0.4 on appropriate age groups; b. Between the minimum spawning biomass level and the precautionary spawning biomass level, the TACs shall not exceed a level corresponding to a fishing mortality rate on appropriate age groups equal to the following formula: (0.2 * (Precautionary spawning biomass level - spawning biomass) / (Precautionary spawning biomass level - minimum spawning biomass level)) c. At or below the limit spawning biomass level, the TAC shall not exceed a level corresponding to a fishing mortality rate of 0.2 on appropriate age groups. 2. Notwithstanding paragraphs 2 and 3, the TAC for 2010 and subsequent years shall not be set at a level that is more than 20 % below or above the TACs established in the previous year. 3. Where the stock has been exploited at a fishing mortality rate close to 0.4 during three successive years, the parameters of this plan shall be reviewed on the basis of advice from ICES in order to ensure exploitation at maximum sustainable yield. 4. The TAC shall be calculated by deducting the following quantities from the total removals of cod that are advised by ICES as corresponding to the fishing mortality rates consistent with the management plan: a. A quantity of fish equivalent to the expected discards of cod from the stock concerned; b. A quantity corresponding to other relevant sources of cod mortality. 5. The Parties agree to adopt values for the minimum spawning biomass level (70,000 tonnes), the precautionary biomass level (150,000 tonnes) and to review these quantities as appropriate in the light of ICES advice. Procedure for setting TACs in data-poor circumstances 6. If, due to a lack of sufficiently precise and representative information, it is not possible to implement the provisions in paragraphs 3 to 6, the TAC will be set according to the following procedure. a. If the scientific advice recommends that the catches of cod should be reduced to the lowest possible level the TAC shall be reduced by 25 % with respect to the TAC for the preceding year. b. In all other cases the TAC shall be reduced by 15 % with respect to the TAC for the previous year, unless the scientific advice recommends otherwise. This plan shall be subject to triennial review, the first of which will take place before 31 December It enters into force on 1 January The main changes between this and the plan of 2004 is the phasing (transitional and long-term phase) and the inclusion of an F reduction fraction, 40 ICES Advice 2009, Book 6

45 EU management plan In December 2008 the European Council agreed on a new cod management plan implementing the new system of effort management and a target fishing mortality of 0.4 (EC 1342/2008). The HCR for setting TAC for the North Sea cod stock are as follows: Article 7 1.(a) and 1.(b) are required for interpretation of Article 8. Article 7: Procedure for setting TACs for cod stocks in the Kattegat the west of Scotland and the Irish Sea 1. Each year, the Council shall decide on the TAC for the following year for each of the cod stocks in the Kattegat, the west of Scotland and the Irish Sea. The TAC shall be calculated by deducting the following quantities from the total removals of cod that are forecast by STECF as corresponding to the fishing mortality rates referred to in paragraphs 2 and 3: (a) a quantity of fish equivalent to the expected discards of cod from the stock concerned; (b) as appropriate a quantity corresponding to other sources of cod mortality caused by fishing to be fixed on the basis of a proposal from the Commission. [ ] Article 8: Procedure for setting TACs for the cod stock in the North Sea, the Skagerrak and the eastern Channel 1. Each year, the Council shall decide on the TACs for the cod stock in the North Sea, the Skagerrak and the eastern Channel. The TACs shall be calculated by applying the reduction rules set out in Article 7 paragraph 1(a) and (b). 2. The TACs shall initially be calculated in accordance with paragraphs 3 and 5. From the year where the TACs resulting from the application of paragraphs 3 and 5 would be lower than the TACs resulting from the application of paragraphs 4 and 5, the TACs shall be calculated according to the paragraphs 4 and Initially, the TACs shall not exceed a level corresponding to a fishing mortality which is a fraction of the estimate of fishing mortality on appropriate age groups in 2008 as follows: 75 % for the TACs in 2009, 65 % for the TACs in 2010, and applying successive decrements of 10 % for the following years. 4. Subsequently, if the size of the stock on 1 January of the year prior to the year of application of the TACs is: (a) above the precautionary spawning biomass level, the TACs shall correspond to a fishing mortality rate of 0,4 on appropriate age groups; (b) between the minimum spawning biomass level and the precautionary spawning biomass level, the TACs shall not exceed a level corresponding to a fishing mortality rate on appropriate age groups equal to the following formula: 0,4 (0,2 * (Precautionary spawning biomass level spawning biomass) / (Precautionary spawning biomass level minimum spawning biomass level)) (c) at or below the limit spawning biomass level, the TACs shall not exceed a level corresponding to a fishing mortality rate of 0,2 on appropriate age groups. 5. Notwithstanding paragraphs 3 and 4, the Council shall not set the TACs for 2010 and subsequent years at a level that is more than 20 % below or above the TACs established in the previous year. 6. Where the cod stock referred to in paragraph 1 has been exploited at a fishing mortality rate close to 0,4 during three successive years, the Commission shall evaluate the application of this Article and, where appropriate, propose relevant measures to amend it in order to ensure exploitation at maximum sustainable yield. Article 9: Procedure for setting TACs in poor data conditions Where, due to lack of sufficiently accurate and representative information, STECF is not able to give advice allowing the Council to set the TACs in accordance with Articles 7 or 8, the Council shall decide as follows: (a) where STECF advises that the catches of cod should be reduced to the lowest possible level, the TACs shall be set according to a 25 % reduction compared to the TAC in the previous year; (b) in all other cases the TACs shall be set according to a 15 % reduction compared to the TAC in the previous year, unless STECF advises that this is not appropriate. Article 10: Adaptation of measures 1. When the target fishing mortality rate in Article 5(2) has been reached or in the event that STECF advises that this target, or the minimum and precautionary spawning biomass levels in Article 6 or the levels of fishing mortality rates given in Article 7(2) are no longer appropriate in order to maintain a low risk of stock depletion and a maximum sustainable yield, the Council shall decide on new values for these levels. ICES Advice 2009, Book 6 41

46 2. In the event that STECF advises that any of the cod stocks is failing to recover properly, the Council shall take a decision which: (a) sets the TAC for the relevant stock at a level lower than that provided for in Articles 7, 8 and 9; (b) sets the maximum allowable fishing effort at a level lower than that provided for in Article 12; (c) establishes associated conditions as appropriate. 42 ICES Advice 2009, Book 6

47 6.4.3 Haddock in Subarea IV (North Sea) and Division IIIa West (Skagerrak) Corrected November 2009 State of the stock Spawning biomass in relation to precautionary limits Full reproductive capacity Fishing mortality in relation to precautionary limits Fishing mortality in relation to high long-term yield Fishing mortality in relation to management target Harvested sustainably Appropriate Below target Comment Based on the most recent estimate of SSB (in 2009) and fishing mortality (in 2008), ICES classifies the stock as having full reproductive capacity and being harvested sustainably. SSB in 2009 is estimated to be above B pa, although SSB has been declining since Fishing mortality in 2008 is estimated to be below F pa, and below the target F HCR (0.3) specified in the EU Norway management plan. Recruitment is characterized by occasional large yield classes, the last of which was the strong 1999 year class. Apart from the 2005 year class which is about average, recent recruitment has been poor. Management objectives In 1999 the EU and Norway agreed to implement a long-term management plan for the haddock stock, which is consistent with the precautionary approach and which is intended to constrain harvesting within safe biological limits (SSB > B lim ) and is designed to provide for sustainable fisheries and high potential yield (F HCR = 0.3). A revised management plan was implemented in January 2009 (Annex 6.4.3). The main elements of the plan are a target F of 0.3 with a limit of 15% change in TAC provided SSB is maintained above t. If SSB is between t and t, F is reduced in line with SSB to reach F = 0.1 at SSB= t. If SSB is at t or below, F is 0.1. Interannual quota flexibility is permitted, with a maximum of ±10% transfer of quota between years. ICES has evaluated this EU Norway management plan and concluded that the target F HCR = 0.3 with TAC constraint ±15% leads on average to a <5% risk of B < B lim within the next 20 years. Increasing the target F HCR increases the risk. Although the management plan has not been fully tested (e.g. at lower fishing mortalities), ICES concludes that the management plan can provisionally be accepted as precautionary and be used as the basis for advice. Interannual quota flexibility has also been evaluated and it is concluded that this has no significant impact on sustainability. Reference points Precautionary approach Type Value Technical basis B lim t Smoothed B loss. B pa t B pa = 1.4 * B lim. F lim 1.0 F lim = 1.4 * F pa. F pa % probability that SSB MT < B pa. Targets F HCR 0.3 Based on HCR simulations and agreed in the management plan (unchanged since 2007) Yield and spawning biomass per Recruit F-reference points Yield-per-recruit and SSB-per-recruit analyses are unstable between recent years due to variation in the selection pattern; therefore, no values are presented here. An HCR evaluation has shown that candidates for reference points consistent with high long-term yields and a low risk of depleting the productive potential of the stock can be found at F = 0.3. ICES Advice 2009, Book 6 43

48 Single-stock exploitation boundaries * Considering the options below, ICES advises on the basis of the management plan that implies landings in 2010 of t, including industrial bycatch. Exploitation boundaries in relation to existing management plans Following the agreed management plan implies landings in 2010 of t, which is expected to lead to an SSB of t in The constraint on interannual TAC variability (±15%) is invoked in this case: the suggested 2010 landings represent a 15% decrease from the 2009 quota. The management plan can be provisionally accepted as precautionary. Exploitation boundaries in relation to high long-term yield, low risk of depletion of production potential, and considering ecosystem effects The current fishing mortality is estimated at 0.23, which is below the target rate expected to lead to high long-term yields (F = 0.3). Exploitation boundaries in relation to precautionary reference points Catches of t implying landings of less than t in 2010 would reduce SSB in 2011 to B pa corresponding to a threefold increase of fishing mortality. * Corrections made in November are presented in bold. 44 ICES Advice 2009, Book 6

49 ICES Advice 2009, Book 6 45 Short-term implications Outlook for 2010 Basis: F(2009) = TAC constraint = 0.23; SSB (2010) = 204; HC landings (2009) = 45; Discards (2009) = 8; Industrial bycatch (2009) = 0.2 Rationale Human consumption Basis F (2010) F HC (2010) F disc (2010) F ind. Bycatch Discards Ind. Bycatch Catch (2010) SSB (2011) %SSB change 1) %TAC change 2) (2010) (2010) (2010) (2010) Zero catch 0 F = % -100% Status quo 30 Fsq % -33% Target reference point 35 F(target) (Fsq*1.19) % -21% Agreed management plan 38 Management plan (15% quota cut) % -15% (Fsq *1.3) High long-term yield 49 F0.1 (Fsq*1.79) % 10% 9 Fsq * % -80% 22 Fsq * % -52% 40 Fsq * % -10% 55 Fsq * % 23% Status quo 57 Fsq * % 28% 66 Fsq * % 48% 72 Fpa (Fsq * 2.8) % 61% 76 Bpa (Fsq * 3.0) % 70% 77 Fsq * % 72% 85 Fsq * % 89% Units: 000 tonnes. Shaded scenarios are not considered consistent with the precautionary approach. Under the assumption that effort is linearly related to fishing mortality 1) SSB 2011 relative to SSB ) Human Consumption 2010 relative to TAC 2009 The landings in Division IIIa are calculated as 6% of the combined area total. The figure 6% has been used as the basis of the TAC split for the past 3 years Corrections made in November are presented in bold. ICES Advice 2009, Book 6 45

50 Management considerations Adherence to the EU Norway management plan has contributed to lower fishing mortality levels, increased yield and greatly improved stability of yield. As the 2005 year class entered the fishery, discards were fairly substantial in 2006 and 2007, although they were considerably lower in Further improvements to gear selectivity measures, allowing for the release of small fish, would be highly beneficial not only for the haddock stock, but also for the survival of juveniles of other species that occur in mixed fisheries along with haddock. Haddock is a specific target for some fleets, but is also caught as part of a mixed fishery catching cod, whiting and Nephrops. For management to be effective, both species-specific assessments and the latest developments in mixed fisheries approaches need to be considered. A reduction in direct effort on one stock may lead to a reduction or an increase in effort on another and, hence, the implications of any changes need to be identified and carefully evaluated. Estimates of haddock bycatch in the industrial fishery are provided in the catch option table. These are low values based on the assumption of a similar bycatch rate to that observed in previous years, when the industrial fisheries were at a low level. A larger catch allocation for bycatch may be required if industrial effort increases (see Norway pout advice section ). The advice for this stock is given for Subarea IV (North Sea) and Division IIIaN (Skagerrak), while the TACs for this stock are set for Division IIa and Subarea IV, and the whole of Subarea III, respectively. ICES has developed a generic approach to evaluate whether new survey information that becomes available in September forms a basis to update the advice. If this is the case, ICES will publish new advice in November Management plan evaluations The evaluations of the management plan that were carried out during 2007 used a recruitment model which is thought to capture the sporadic nature of haddock recruitment. On this basis, a target F = 0.3 with TAC constraint ±15% leads to a low risk of <12% in any year, and a mean risk of 5% over all years of B < B lim over the next 20 years. Lower Fs lead to lower risks. Interannual quota flexibility has also been evaluated and it is concluded that this has no significant impact on sustainability. Although the management plan has not been fully tested (e.g. the effect of the new rule for low biomass is not well known), ICES concludes that the management plan can be provisionally accepted as precautionary and can be used as the basis for advice. Factors affecting the fisheries and the stock Regulation and their effects EU technical regulations in force are contained in Council Regulation (EC) 850/98 and its amendments. The regulation prescribes the minimum target species composition for different mesh size ranges. In 2001, haddock in the whole of NEAFC region 2 were a legitimate target species for towed gears with a minimum codend mesh size of 100 mm. As part of the cod recovery measures, the EU and Norway introduced additional technical measures from 1 January 2002 (EC 2056/2001). The basic minimum mesh size for towed gears for cod from 2002 was 120 mm, although in a transitional arrangement running until 31 December 2002 vessels were allowed to exploit cod with 110 mm codends, provided that the trawl was fitted with a 90 mm square-mesh panel and the catch composition of cod retained on-board was not greater than 30% by weight of the total catch. From 1 January 2003, the basic minimum mesh size for towed gears for cod was 120 mm. The minimum mesh size for vessels targeting haddock in Norwegian waters is also 120 mm. The effect of the measures has been to reduce fishing mortality on haddock to sustainable levels and to maintain the spawning biomass above B pa despite a prolonged series of poor recruitments. Effort restrictions in the EC were introduced in 2003 (annual annexes to the TAC regulations) for the protection of the North Sea (?) cod stock. In 2009, the management program switched from a days at sea to a kw/day system (2009 Council Regulation (EC) N 43/2009), in which different amounts of kw/days are allocated within each area by Member State to different groups of vessels depending on gear and mesh size. In 2008, STECF indicated that overall effort (kw/days) by demersal trawls, seines and beam trawls had been substantially reduced since Fishing mortality declined between 2003 and 2007 concomitant with this effort reduction, but F increased again in 2008 despite a further nominal reduction in effort. Marked changes have also occurred in the use of the different mesh size categories by demersal trawlers. A sharp reduction has occurred in the use of mesh sizes between 100mm and 119mm, while a 46 ICES Advice 2009, Book 6

51 pronounced increase is apparent in the use of mesh sizes of 120mm and greater. As well, a general increase in effort has been observed in vessels using mesh sizes of 70-89mm and 90-99mm. Scotland implemented in February 2008 a national scheme known as the Conservation Credits Scheme. The principle of this two-part scheme involves additional time at sea in return for the adoption of measures which aims to reduce mortality on cod and lead to a reduction in discard numbers. ICES has not yet been able to evaluate the consequences of these measures. Despite their introduction, ICES notes that during the initial year of operation (2008) cod discarding rates increased substantially. Changes in fishing technology and fishing patterns The change in mesh size (to 120 mm) might be expected to shift exploitation patterns to older ages and increase the weight-at-age for retained fish from younger age classes. While reduced exploitation on more abundant cohorts can be seen, overall improvements in the exploitation pattern have not been observed. It was not possible to determine if this is due to confounding effects from other fleet segments. The effort in the UK large-mesh demersal trawl fleet category (>100 mm, 4A) has been reduced by decommissioning and days-at-sea regulations to 40% of the levels recorded in the EU reference year of There was a movement of effort into the mm sector to increase days-at-sea in 2002 and 2003, but the level of effort in this sector stabilized in Scientific basis Data and methods The age-based assessment model (XSA) is calibrated with three survey indices. Discards and industrial bycatch data were included in the assessment. Discards were estimated from the discards sampling programme from several countries, with most observations coming from Scotland. The samples were then raised to the total international fleet. Information from the fishing industry The report of the North Sea Fishers Survey (Laurenson 2008) shows that the industry perception of haddock abundance in the main haddock fishing areas (1 and 2) is of stabilization, which concurs with the indications from the assessment of a temporary slowing of the rate of decline in SSB with the growth of the 2005 year class. The previous decline in haddock abundance estimated by the assessment is not apparent in the Survey. This suggests that demersal vessels may be able to maintain good catch rates of haddock in spite of declining abundance. Uncertainties in assessment and forecast The trends indicated by the assessment are in agreement with the surveys. The assessment and forecast are largely influenced by the moderate 2005 year class. Comparison with previous assessment and advice The basis of the assessment and advice is the same as last year. The assessment is sensitive to the estimation of a few large cohorts, so the variability in estimates among assessment years is to be expected. There are no indications of assessment bias. Source of information Report of the Working Group on the Assessment of Demersal Stocks in the North Sea and Skagerrak, 6-12 May 2009 (ICES CM 2009/ACOM:10). STECF PLEN EUR EN, ISBN , ISSN , DOI /3484, 2008 ICES Advice 2009, Book 6 47

52 Table Haddock in Subarea IV (North Sea) Single stock exploitation boundaries (advice), management and catch. ICES catches Year ICES Single-stock Predicted Predicted landings Agreed Off. Hum. Disc Indust. Total Advice exploitation boundaries landings corresp. to advice 1 corresp. to singlestock exploitation boundaries 2 TAC lndgs. Cons. Slip. bycatch % of F(85) % of F(86); TAC 1989 Reduce decline in SSB; TAC; protect juveniles % of F(88); TAC % of effort (89) % of effort (89) % of effort (89) Significant reduction in effort; mixed fishery 1995 Significant reduction in effort; mixed fishery 1996 Mixed fishery to be taken into account 1997 Mixed fishery to be taken into account 1998 No increase in F Reduction of 10% F(95 97) 2000 F less than F pa < F less than F pa < F less than F pa < No cod catches Mixed fisheries F should be * No forecast consideration below F pa 2005 Mixed fisheries F should be * consideration below F pa 2006 Mixed fisheries F should be * consideration below Mixed fisheries F should be * consideration below Mixed fisheries 15% TAC * consideration reduction TA 2009 Mixed fisheries consideration Apply management * Mixed fisheries consideration plan Apply management plan * 38 3 Weights in 000 t. 1 Only pertaining to the North Sea. 2 For the whole stock (Division IIIaN and Subarea IV). 3 Including industrial bycatch. * Single-stock boundary and the exploitation of this stock should be conducted in the context of mixed fisheries protecting stocks outside safe biological limits. 48 ICES Advice 2009, Book 6

53 Table Haddock in Division IIIaW (Skagerrak) Single stock exploitation boundaries (advice), management and landings. Year ICES Advice Single-stock exploitation boundaries Predicted landings corresp. to advice Predicted landings corresp to singlestock exploitation boundaries Agreed TAC ICES landings Hum. Indust. Total Cons. bycatch 1987 Precautionary TAC Precautionary TAC Precautionary TAC Precautionary TAC Precautionary TAC TAC Precautionary TAC Precautionary TAC If required, precautionary TAC; link to North Sea 1996 If required, precautionary TAC; link to North Sea 1997 Combined advice with North Sea 1998 Combined advice with North Sea 1999 Combined advice with North Sea 2000 Combined advice with North Sea 2001 Combined advice with North Sea 2002 Combined advice with North Sea 2003 Combined advice with North Sea 2004 Combined advice with North Sea 2005 Combined advice with North Sea 2006 Combined advice with North Sea 2007 Combined advice with North Sea 2008 Combined advice with North Sea 2009 Combined advice with North Sea 2010 Combined advice with North Sea Weights in 000 t. n/a = not available. F should be below F pa F should be below F pa F should be below 0.3 F should be below % TAC reduction Apply management plan Apply management plan < < < n/a 1.8 No forecast n/a ICES Advice 2009, Book 6 49

54 Figure Haddock in Subarea IV (North Sea) and Division IIIaW (Skagerrak). Summary plots. The dotted horizontal lines indicate F pa (top right plot) and B pa (bottom left plot), while the solid ones indicate F lim (top right plot) and B lim (bottom left plot). Stock - Recruitment Recruitment (age 0) in billions SSB-Rec. Blim Bpa SSB in 1000 t Figure Haddock in Subarea IV (North Sea) and Division IIIaW (Skagerrak). Stock recruitment plot. 50 ICES Advice 2009, Book 6

55 Figure Haddock in Subarea IV (North Sea) and Division IIIaW (Skagerrak). Results of 2008 North Sea Stock Survey. Each plot presents a summary of the responses by North Sea roundfish reporting area. Haddock in Subarea IV (North Sea) and Division IIIa West (Skagerrak) 600 SSB ('000 tonnes) 1.40 Fishing mortality: Billions Recruitment. Age: Figure Haddock in Subarea IV (North Sea) and Division IIIaW (Skagerrak). Comparison of current assessment with previous assessments. ICES Advice 2009, Book 6 51

56 Table Haddock in Subarea IV (North Sea) and Division IIIaW (Skagerrak). Catches/landings by country and area. Sum of Landings Year ICES area Country Division IIIa Belgium Denmark Faeroe Islands Germany Netherlands Norway Portugal Sweden UK - Eng+Wales+N.Irl UK - Scotland Division IIIa Total WG Division IIIa WG estimates of discards WG estimates of IBC WG estimates of landings WG estimates of total catch WG Division IIIa Total Subarea IV Belgium Denmark Faeroe Islands France Germany Greenland Ireland Netherlands Norway Poland Portugal Sweden UK - Eng+Wales+N.Irl UK - Scotland UK - all Subarea IV Total WG Subarea IV WG estimates of discards WG estimates of IBC WG estimates of landings WG estimates of total catch WG Subarea IV Total TAC TAC IIIa TAC IV TAC Total ICES Advice 2009, Book 6

57 Table Haddock in Subarea IV (North Sea) and Division IIIaW (Skagerrak). Summary of stock assessment. RECRUITMENT TSB SSB CATCH LANDINGS DISCARDS IBC YIELD/SSB MEAN F(2-4) Units Thousands Tonnes Tonnes Tonnes Tonnes Tonnes Tonnes 3 Corrections made in November are presented in bold. The relating figures have not been updated from the June advice. ICES Advice 2009, Book 6 53

58 Annex 6.4.3a EU and Norway Management plan The plan shall consist of the following elements: 1. Every effort shall be made to maintain a minimum level of Spawning Stock Biomass greater than 100,000 tonnes (B lim ). 2. For 2009 and subsequent years the Parties agreed to restrict their fishing on the basis of a TAC consistent with a fishing mortality rate of no more than 0.3 for appropriate age-groups, when the SSB in the end of the year in which the TAC is applied is estimated above 140,000 tonnes (B pa ). 3. Where the rule in paragraph 2 would lead to a TAC, which deviates by more than 15 % from the TAC of the preceding year, the Parties shall establish a TAC that is no more than 15 % greater or 15 % less than the TAC of the preceding year. 4. Where the SSB referred to in paragraph 2 is estimated to be below B pa but above B lim the TAC shall not exceed a level which will result in a fishing mortality rate equal to *(B pa -SSB)/(Bpa-Blim). This consideration overrides paragraph Where the SSB referred to in paragraph 2 is estimated to be below Blim the TAC shall be set at a level corresponding to a total fishing mortality rate of no more than 0.1. This consideration overrides paragraph In the event that ICES advises that changes are required to the precautionary reference points B pa (140,000t) or B lim, (100,000t) the Parties shall meet to review paragraphs In order to reduce discarding and to increase the spawning stock biomass and the yield of haddock, the Parties agreed that the exploitation pattern shall, while recalling that other demersal species are harvested in these fisheries, be improved in the light of new scientific advice from inter alia ICES. 8. No later than 31 December 2010, the parties shall review the arrangements in paragraphs 1 to 7 in order to ensure that they are consistent with the objective of the plan. This review shall be conducted after obtaining inter alia advice from ICES concerning the performance of the plan in relation to its objective. 9. This arrangement enters into force on 1 January ICES Advice 2009, Book 6

59 6.4.4 Whiting in Division IIIa (Skagerrak Kattegat) Single-stock exploitation boundaries The landing data available for this stock give insufficient reason to change the advice from The advice on this stock for the fishery in 2010 is therefore the same as the advice given in 2008 for the 2009 fishery: The landings should be less than the average ( ) landings of 1050 t as a precautionary value to restrict the potential for significant reexpansion of the fishery and misreporting from other regions. This advice will be updated in Source of information Report of the Working Group on the Assessment of Demersal Stocks in the North Sea and Skagerrak, 6-12 May 2009 ICES CM 2009/ACOM:10. Year ICES Advice / Single-Stock Exploitation Boundaries 2) Predicted catch corresp. to advice Predicted catch corresp. to Single- Stock Exploitation Boundaries Agreed TAC ICES Catch 1) 1987 Precautionary TAC Precautionary TAC Precautionary TAC Precautionary TAC TAC No advice Precautionary TAC If required, precautionary TAC If required, precautionary TAC If required, precautionary TAC If required, TAC equal to recent catches No advice TAC, average period TAC, average period TAC, average period TAC, average period TAC, average period TAC, average period average period ) average period ) average period ) Recent average catches 2) Same advice as last year 2) Same advice as last year 2) Weights in 000 t. 1) Includes bycatch in small-mesh industrial fishery. 2) Single-stock boundary, and the exploitation of this stock should be conducted in the context of mixed fisheries protecting stocks outside safe biological limits. ICES Advice 2009, Book 6 55

60 Table Whiting in Division IIIa. Nominal landings (t) by country as supplied by the Working Group. Year Denmark (1) Norway Sweden Others Total , , , , , , , , , , , , , , ,654 Total consumption Total industrial Total ,027 23,915 24, , , ,183 39,758 40, , ,311 23,505 24, , , ,036 12,102 13, , , ,967 12, , ,979 12, , ,880 16, , ,872 11, , ,662 12, , ,016 17,829 18, , ,463 13, , ,340 3, , ,987 2, , ,900 2, , ,549 2, , ,235 1, , , , , , , , , , n/a n/a n/a n/a Values from 1992 updated by WGNSSK (2007) 56 ICES Advice 2009, Book 6

61 6.4.5 Whiting in Subarea IV (North Sea) and Division VIId (Eastern Channel) Corrected November 2009 State of the stock Spawning biomass in relation to precautionary limits Fishing mortality in relation to precautionary limits Fishing mortality in relation to high longterm yield Undefined Undefined Undefined NA Fishing mortality in relation to agreed target Comments In the absence of defined reference points, the state of the stock cannot be evaluated. An analytical assessment estimates SSB in 2009 as being near the lowest level since the beginning of the time-series in Fishing mortality has declined from , but increased in recent years. Recruitment has been very low since 2002, with an indication of a modest improvment in the 2007 year class. Management objectives There are no explicit management objectives for this stock. Reference points No precautionary reference points are set for this stock. Yield and spawning biomass per Recruit F-reference points (2009): Fish Mort Yield/R SSB/R Ages 2-6 Average last 3 years Fmax N/A F0.1 * Fmed N/A F 0.1 was revised in this year s assessment; further work is being conducted on the interpretation of F 0.1 for this stock. Candidates reference points consistent with high long-term yields and a low risk of depleting the productive potential of the stock cannot be recommended since fishing near F 0.1 = 0.57 in the past was accompanied with marked declines in the stock. Single-stock exploitation boundaries * Because no reference points are available, ICES advises on the basis of precautionary considerations that a significant reduction of the TAC is required to remedy the decline in SSB. An immediate TAC reduction of 64 % ( t Total catch, t human consumption catch) is needed to stabilize the stock, but rebuilding would require a further reduction. * Corrections made in November are presented in bold. ICES Advice 2009, Book 6 57

62 Short-term implications Outlook for 2010 Basis: F (2009) = Mean F ( ) scaled to F (2008) = 0.47; R(2009) = RCT3 = 1297; SSB (2009) = 94; SSB (2010) = 89; landings (2009) = 19; discards (2009) = 11. HC Total F F F F Disc. Ind. % TAC SSB %SSB Rationale Catch Catch Basis Total HC Disc. Ind. Catch Catch 2011 change 1) change 2) Zero -100% % catch *Fsq % -89% Status -78% *Fsq % quo *Fsq % -68% *Fsq % -64% *Fsq % -48% *Fsq % -38% *Fsq % -29% *Fsq % -20% *Fsq % -15% Fsq % -4% *Fsq % 4% *Fsq % 12% Weights in 000 tonnes. 1) SSB 2011 relative to SSB ) Human consumption for IV (80% of HC Catch) 2010 relative to TAC for area IV and IIa in The human consumption landings in Divisions IV and VIId are calculated as 80% and 20% of the combined area total on the basis of estimates of landings for the past three years. Management considerations Catches of whiting have been declining since 1980 (from t in 1980 to t in 2008, including discards and industrial bycatch). Distribution maps of survey IBTS indices show a change in distribution of the stock which is now located mainly in the northwestern North Sea. Catch rates from localized fleets may not represent trends in the overall North Sea and English Channel population (Figure ). The localized distribution of the population is known to be resulting in substantial differences in the quota uptake rate. This is likely to result in localized discarding problems that should be monitored carefully. Whiting are caught in mixed demersal roundfish fisheries, fisheries targeting flatfish, the Nephrops fisheries, and the Norway pout fishery. For management to be effective, both species-specific assessments and the latest developments in mixed fisheries approaches need to be considered. A reduction in direct effort on one stock may lead to a reduction or an increase in effort on another and, hence, the implications of any changes need to be identified and carefully evaluated. The current minimum mesh-size in the targeted demersal roundfish fishery in the northern North Sea has resulted in reduced discards from that sector compared with the historical discard rates. Mortality has increased on younger ages due to increased discarding in the recent year as a result of recent changes in fleet dynamics of Nephrops fleets and small mesh fisheries in the southern North Sea. The bycatch of whiting in the industrial Norway pout and sandeel fisheries is dependent on activity in that fishery, which has recently declined after strong reductions in the fisheries. These are low values based on the assumption of a similar bycatch rate to that observed in previous years, when the industrial fisheries were at a low level. A larger catch allocation for bycatch may be required if industrial effort increases (see Norway pout advice Section ). Corrections made in November are presented in bold. 58 ICES Advice 2009, Book 6

63 Catches of whiting in the North Sea are also likely to be affected by the effort reduction seen in the targeted demersal roundfish and flatfish fisheries, although this will in part be offset by increases in the number of vessels switching to small mesh fisheries. Recent measures to improve survival of young cod, such as the Scottish Credit Conservation Scheme, and increased uptake of more selective gear in the North Sea and Skagerrak, should be encouraged for whiting. Following the EU Commission consultation paper on TACs for 2010 (COM(2009) 224, 12 May 2009) this stock would be categorised based on the average of SSB in the last 2 years compared to the average of the 3 preceding years. For this stock, this shows a reduction of 24%, resulting in a 15% reduction of the TAC. ICES has not evaluated this rule in relation to the precautionary approach. ICES has developed a generic approach to evaluate whether new survey information that becomes available in September forms a basis to update the advice. If this is the case, ICES will publish new advice in November Impact of fisheries on the ecosystems The effect on the benthic invertebrate community in the northern North Sea from all otter trawling is estimated to represent an annual mortality of approximately 25% of the standing-crop biomass. The MAFCONS STECF datasets suggest that otter trawl effort directed at fish has declined since 1999 (Greenstreet et al., 2007). Factors affecting the fisheries and the stock Regulations and their effects The human consumption TAC for whiting has not been taken for at least 20 years. The minimum mesh size increased to 120 mm in the northern area in 2002 and this may have contributed to the substantial decrease in reported landings. Landings compositions from the northern area, in 2006 and 2007, indicate improved survival of older ages. In addition, the total number of fish discarded appears to have been significantly reduced since 2003, from around 60% in 2003 to around 47% in Effort restrictions in the EC were introduced in 2003 (annual annexes to the TAC regulations) for the protection of the North Sea (?) cod stock. In 2009, the management program switched from a days at sea to a kw/day system (2009 Council Regulation (EC) N 43/2009), in which different amounts of kw/days are allocated within each area by Member State to different groups of vessels depending on gear and mesh size. In 2008, STECF indicated that overall effort (kw/days) by demersal trawls, seines and beam trawls had been substantially reduced since Fishing mortality declined between 2003 and 2007 concomitant with this effort reduction, but F increased again in 2008 despite a further nominal reduction in effort. Marked changes have also occurred in the use of the different mesh size categories by demersal trawlers. A sharp reduction has occurred in the use of mesh sizes between 100mm and 119mm, while a pronounced increase is apparent in the use of mesh sizes of 120mm and greater. As well, a general increase in effort has been observed in vessels using mesh sizes of 70-89mm and 90-99mm. Scotland implemented in February 2008 a national scheme known as the Conservation Credits Scheme. The principle of this two-part scheme involves additional time at sea in return for the adoption of measures which aims to reduce mortality on cod and lead to a reduction in discard numbers. ICES has not yet been able to evaluate the consequences of these measures. Despite their introduction, ICES notes that during the initial year of operation (2008) cod discarding rates increased substantially. Changes in fishing technology and fishing patterns The use of bigger meshes in the top panel of Belgium beam trawler gear is expected to reduce the bycatch of roundfish species, especially haddock and whiting. Scientific basis Data and methods The stock assessment is based on an XSA assessment, calibrated with two survey indices. Commercial catch-at-age data were disaggregated into human consumption, discards, and industrial bycatch components. Partial fishing mortalities from these catch components were calculated from their average contribution over This could not be done on an area basis. Discards were estimated based on data from Scotland, England, Denmark and Germany and raised to the total international fleet in the North Sea. Discard information is now available for the years 2003 to 2008 for a major ICES Advice 2009, Book 6 59

64 component of the catch from French fleets fishing in Areas IV and VIId, these data will be incorporated in next years assessment. There are considerable discrepancies in stock trends prior to 1990 between the survey time-series and the assessment based on commercial catch data. Calibration data prior to 1990 were therefore omitted from the time-series. Information from the fishing industry The report of the North Sea Fishers Survey (Laurenson 2008) shows that the industry perception of whiting abundance since 2001 in general is at odds with the assessment, only no change or more was reported and in contrast the assessment indicates a continuously declining stock. However, the perception of an increasing stock around the eastern English coast (areas 4 and 5) is reflected in survey distribution plots. There is also a perception of increased discards in these areas. The UK industry has highlighted the continuing problem of the effect of the reduced TAC for whiting in specific areas of the North Sea where whiting abundance has been increasing in contrast to the decline in the wider North Sea. Whiting has been attracting high market value in the last three years and the cost of whiting quota has increased substantially resulting in higher discarding in some areas of high abundance due to the unavailability of affordable quota. This observation is consistent with the ICES advice that the localized distribution of the population is known to be resulting in substantial differences in the quota uptake rate. Uncertainties in assessment and forecast Discard estimates are based largely on the Scottish and English sampling programme, with the Scottish data getting three times the weight in the estimation but landing only approximately 50% of the total landings. Scottish sampling is mainly in the northern area. Because the fishery in the southern area is mostly carried out with different gears and smaller mesh sizes, this estmation will be a source of uncertainty in the assessment.. Comparison with previous assessment and advice The natural mortality values used in the assessment have been revised based on new estimates from the multi-species model. This has resulted in a substantial increase in the level of recruitment and reduction in the historic values of spawning biomass with a relatively minor reduction in the level of fishing mortality. The trends and the conclusions drawn from them remain unchanged. The basis of the advice has changed: the 2008 advice aimed for Fmax, this year the advice should result in a stable SSB. Sources of information Report of the Working Group on the Assessment of Demersal Stocks in the North Sea and Skagerrak, 6-12 May ICES CM 2009/ACOM:10. Greenstreet, S., Robinson, L., Piet, G., Craeymeersch, J., Callaway, R., Reiss, H., Ehrich, S., Kröncke, I., Fraser, H., Lancaster, J., Jørgensen, L., and Goffin, A The ecological disturbance caused by fishing in the North Sea. Fisheries Research Services, Aberdeen, U.K. Collaborative Report No 04/ pp. STECF PLEN EUR EN, ISBN , ISSN , DOI /3484, ICES Advice 2009, Book 6

65 ICES Advice 2009, Book 6 61 Table Year ICES Advice Whiting in Subarea IV (North Sea). Single-stock exploitation boundaries (advice), management, and catch. Single-Stock Exploitation Boundaries Predicted landings corresp. to single-stock expl. boundaries advice** ICES Advice 2009, Book 6 61 Agreed TAC Off. Lndgs. ICES figures Hum. Indust. Disc. Total Cons. bycatch slip. catch 1989 Protect juveniles % of F(88); TAC % of effort (89) % of effort (89) % of effort (89) Significant reduction in effort; mixed fishery Significant reduction in effort; mixed fishery Mixed fishery; take into account cod advice Mixed fishery; take into account cod advice No increase from 1996 level at least 20% reduction of F(95 97) lowest possible catch % reduction of F(97 99) F not larger than No cod catches No cod catches *) Fishing mortality in 2004 should be < F pa No increase compared to recent years No cod catches *) Less than recent avg No cod catches *) Less than recent avg < No cod catches *) Less than recent avg < No cod catches Less than recent avg < No cod catches *) F < F max < No cod catches *) Stable SSB <7.4 Weights in 000 t. *) Single-stock boundary, and the exploitation of this stock should be conducted in the context of mixed fisheries protecting stocks outside safe biological limits. **) including Division VIId from 2005 onwards.

66 62 ICES Advice 2009, Book 6 Table Year ICES Advice Whiting in Division VIId (Eastern Channel). Single-stock exploitation boundaries (advice), management, and catch/landings. Single-Stock Exploitation Boundaries Predicted landings corresp. to single-stock expl. boundaries advice** Agreed TAC 1 Official landings 1989 Precautionary TAC - - n/a No increase in F; TAC n/a F sq ; TAC n/a If required, precautionary TAC No basis for advice No long-term gains in increasing F Significant reduction in effort; link to North S Reference made to North Sea advice Reference made to North Sea advice Reference made to North Sea advice Reference made to North Sea advice n/a Lowest possible catch % reduction of F sq F not larger than 0.37 <= No cod catches No cod catches *) Fishing mortality Catch should not increase should be <F pa compared to recent years No cod catches *) No cod catches *) Less than recent < average 2007 No cod catches *) Less than recent < average 2008 No cod catches *) Less than recent < average 2009 No cod catches *) F < F max < No cod catches *) Stable SSB <7.4 Weights in 000 t. 1 Included in TAC for Subarea VII (except Division VIIa). 2 Including VIIe. *) Single-stock boundary, and the exploitation of this stock should be conducted in the context of mixed fisheries protecting stocks outside safe biological limits. **) Includes both areas (IV and VIId). n/a = Not available. ICES Catch ICES Advice 2008, Book 6

67 Landings Landings in 1000 t F(ages 2-6) Fishing Mortality Recruitment in billions Recruitment (age 1) Figure Whiting in Subarea IV and Division VIId. Summary of stock assessment: landings, fishing mortality, recruitment, and SSB. Predictions are shown shaded. ICES Advice 2009, Book 6 63

68 Stock - Recruitment Recruitment (age 1) in billions SSB in 1000 t Yield and Spawning Stock Biomass per Recruit Yield (dashed line) Fishing Mortality (ages 2-6) SSB (line) Figure Whiting in Subarea IV and Division VIId. Stock recruitment relationship and Yield and SSB per Recruit plot. 64 ICES Advice 2009, Book 6

69 Figure Whiting in Subarea IV and Division VIId. Commercial landings (human consumption and industrial fisheries in tonnes) by ICES statistical rectangle over the years 1984 to The same scaling is used in each map. In the top left plot a + indicates where landings are reported / available in every year ( ), indicates that for some years no landings were reported / available for that square. Danish industrial bycatch was available from French human consumption landings were available from ICES Advice 2009, Book 6 65

70 Figure Whiting in Subarea IV and Division VIId. Results of the North Sea Commission fishers survey Whiting Sub-area IV (North Sea) & Division VIId (Eastern Channel) SSB ('000 tonnes) Fishing mortality: Billions Recruitment. Age: Figure Whiting in Subarea IV and Division VIId. Comparison of current assessment with previous assessments. The change in Recruitment is caused by the use of increased values of natural mortality particularly at age 1 (increased from 0.95 to based on WGSAM, 2008) this is also the cause of the increased SSB. 66 ICES Advice 2009, Book 6

71 Table Whiting in Subarea IV and Division VIId. Catches (in tonnes) by country and by area. Subarea IV Country Belgium Denmark Faroe Islands France Germany Netherlands Norway Sweden UK (E.&W) UK (Scotland) UK (Total) Total Unallocated landings WG estimate of H.Cons landings WG estimate of discards WG estimate of Ind. Bycatch WG estimate of total catch Division VIId Country Belgium France Netherlands UK (E.&W) UK (Scotland) UK (Total) 87 Total Unallocated W.G. estimate ICES Advice 2009, Book 6 67

72 Table Whiting in Subarea IV and Division VIId. Summary of stock assessment. Year Recruitment SSB Landings Catches Mean F Age 1 Ages 2-6 thousands tonnes tonnes Tonnes * Average * survey estimates 3 Corrections made in November are presented in bold. Because this is a marginal difference, the relating figures have not been updated from the June advice. 68 ICES Advice 2009, Book 6

73 6.4.6 Plaice in Division IIIa (Skagerrak Kattegat) Single-stock exploitation boundaries As in 2008, the new analysis available for this stock has not given a reason to change the advice from The advice on this stock for the fishery in 2010 is therefore the same as the advice given over the last 2 years: Landings should not exceed the level recorded in 2006 of 9400 t. In addition, ICES offers the following consideration: In 2007, ICES identified key issues that would need to be resolved before reaching further improvements in the assessment. The various surveys give a reasonably consistent result for the eastern part of the area. The status of the western part is more uncertain, due to potential mixing with North Sea plaice and limited survey coverage. The landings-at-age matrix does not show proper tracking of the cohorts, probably due to i) mixing of the IIIa stock with the North Sea plaice stock on the main fishing ground in southwestern Skagerrak, and ii) uncertainty in ageing due to low sampling levels. In 2009, ICES still considered these issues as outstanding, although uncertainty due to age reading is likely to have decreased in the recent years. This advice will be updated in Source of information Report of the Working Group on the Assessment of Demersal Stocks in the North Sea and Skagerrak, 6-12 May 2009 (ICES CM 2009/ACFM:10). Year ICES Advice Single-stock Exploitation Boundaries Predicted catch corresp. to advice Agreed TAC Kattegat Agreed TAC Skagerrak ICES Landings 1992 TAC Precautionary TAC If required, precautionary TAC If required, precautionary TAC If required, precautionary TAC No advice No increase in F from the present No increase in F from the present F < F pa F < F pa F < F pa F < F pa F < F pa F < F pa < No increase in F < Maintain current < TAC 2008 No increase in catch < Same advice as last year No increase in catch < Same advice as last year No increase in catch <9.4 Weights in 000 t. 1) In March 2002 ACFM revised its advice to 11.6 for both areas combined. 2) The TAC for the two areas combined was adjusted to tonnes in mid ) Single-stock boundary and the exploitation of this stock should be conducted in the context of mixed fisheries. ICES Advice 2009, Book 6 69

74 Table Plaice in Kattegat. Landings in tonnes. Working Group estimates, Year Denmark Sweden Germany Belgium Norway Total , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , ,008 * years landings refers to IIIA 70 ICES Advice 2009, Book 6

75 Table Plaice in Skagerrak. Landings in tonnes. Working Group estimates, Year Denmark Sweden Germany Belgium Norway Netherlands Total , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , ,584 6, , ,511 7, , , , ,190 7, , ,659 7, , ,607 ICES Advice 2009, Book 6 71

76 6.4.7 Plaice in Subarea IV (North Sea) State of the stock Spawning biomass in relation to precautionary limits Full reproductive capacity Fishing mortality in relation to precautionary limits Harvested sustainably Fishing mortality in relation to high long-term yield Overfished Fishing mortality in relation to agreed target Below target Comment Based on the most recent estimate of SSB (in 2009) and fishing mortality (in 2008), ICES classifies the stock as having full reproductive capacity and as being harvested sustainably. SSB is estimated to have increased above the B pa. Fishing mortality is estimated to have decreased to below F pa and F target. Recruitment has been of average strength from 2005 onwards. The recruitment in 2008 is just below the long-term average. Management objectives EC and Norway have no agreed management plan for North Sea plaice. However, the EC has adopted a management plan for flatfish in the North Sea in June 2007 (Council Regulation (EC) No. 676/2007, see Appendix). This plan has two stages. The first stage aims at an annual 10% reduction of fishing mortality in relation to the fishing mortality estimated for the preceding year until an F of 0.3 is reached, with a maximum change in TAC of 15% until the precautionary reference points are reached for both plaice and sole for two successive years. ICES interprets the F for the preceding year as the estimate of F for the year in which the assessment is carried out. The basis for this F estimate in the preceding year will be a constant application of the procedure used by ICES in In the second stage, the management plan aims for exploitation at F = 0.3. ICES has evaluated the agreed long-term management plan (Council Regulation (EC) No. 676/2007) for plaice and sole. For plaice, the management plan evaluation is not yet conclusive with regards to consistency with the precautionary approach. Reference points Precautionary approach Type Value Technical basis B lim t B loss = t, the lowest observed biomass in 1997 as assessed in B pa t Approximately 1.4 B lim. F lim 0.74 F loss for ages 2 6. F pa th percentile of F loss (0.6) and implies that B eq >B 1) pa and a 50% probability that SSB MT ~ B pa. Targets F mgt 0.3 EU management plan (unchanged since 2004, target added in 2008) Yield and spawning biomass per Recruit F-reference points (2009): Fish Mort Yield/R SSB/R Ages 2-6 Average last 3 years Fmax F Fmed A candidate for the reference point consistent with taking high long-term yields and achieving a low risk of depleting the productive potential of the stock is F max. 72 ICES Advice 2009, Book 6

77 Single-stock exploitation boundaries Considering the options below, ICES advises on the basis of the existing EU management plan. Although the evaluation of the plan has not been conclusive, the fishing mortality in 2010 when applying the management plan is expected to give benefits in terms of long-term yield and low risk to the stock compared to fishing at precautionary levels. ICES therefore advises to limit landings to t for the year Exploitation boundaries in relation to existing management plans According to the management plan adopted by the EU in 2007, the fishing mortality in 2010 should be at the target F (= 0.3) with the constraint that the change in TAC should not be more than 15%. In this case the 15% limit is the determining factor, resulting in a TAC of no more than t. Exploitation boundaries in relation to high long term yield, low risk of depletion of production potential and considering ecosystem effects The current total fishing mortality (including discards) is estimated to be 0.25, which is above the rate expected to lead to high long-term yields and low risk of stock depletion (Fmax). Exploitation boundaries in relation to precautionary limits The exploitation boundaries in relation to precautionary limits imply human consumption landings of less than t in 2010, which is expected to maintain SSB above B pa in 2011, while maintaining F below F pa. Short-term implications Outlook for 2010 Basis: F(2009) = mean(f ) scaled to 2008 = 0.246; R(2009) = GM( ) = ; Landings(2009) = 59.5 ; Discards(2009) = 43.8 ; SSB(2010) = 442. Rationale Landings 2010 Basis Disc (2010) Catch (2010) SSB (2011) %SSB change %TAC change F total (2 6) (2010) F HC (2 6) (2010) F disc (2 3) (2010) zero catch 0 F= % -100% High longterm yield 46.4 F(long-term yield) % -16% Eu management 63.8 Fsq* % +15% plan Status quo 17.6 Fsq* % -68% 34.3 Fsq* % -38% 47 Fsq* % -15% 55.6 Fsq* % 0% 59.2 Fsq* % +7% 65.1 Fsq % +17% 77.7 Fsq* % +40% 79.3 Fsq* % +43% 92.9 Fsq* % +67% Fsq* % +91% 118 Fsq* % +113% Fsq*2.44 = Fpa % +149% Fsq* % +307% Weights in 000t. Shaded scenarios are not considered consistent with the precautionary approach. 1) SSB 2011 relative to SSB ) Landings 2010 relative to TAC ICES Advice 2009, Book 6 73

78 Management considerations Plaice is taken by beam trawlers in a mixed fishery with sole in the southern and central part of the North Sea with a minimum mesh size of 80 mm. In other areas plaice is also taken with larger mesh size, and by other gears. Technical measures applicable to the mixed flatfish fishery with beam trawls will affect both sole and plaice. The minimum mesh size of 80 mm selects sole at the minimum landing size. However, this mesh size generates high discards of plaice which are selected from 17 cm, while the minimum landing size is 27 cm. Recent discard estimates indicate fluctuations around 50% discards in weight. Mesh enlargement would reduce the catch of undersized plaice, but would also result in loss of marketable sole. For two succesive years, the stock has been classified within safe precautionary boundaries and thus fullfilled the 1st phase of the management plan. Although the estimates of the SSB and fishing mortality are uncertain, it is evident that the stock has increased considerably and the fishing mortality has been reduced. The increase in the stock has occurred under average recruitment conditions and is not caused by a higher productivity of the stock. The main reason for the increase of the SSB is the reduction of fishing mortality under the present management plan. Also a reduction of capacity in the fleets fishing for plaice, limitation of fishing effort and high fuel prices have contributed to the decrease in fishing mortality. Fishing effort has been substantially reduced since 1995, including the decommissioning of 25 vessels in The reduction in fishing effort is reflected in recent estimates of fishing mortality. There are indications that technical efficiency has increased in this fishery, which may have reduced the effect of the reduction in effort, but this may have been counteracted by decreases in fishing efficiency resulting from reduced fishing speed in an attempt to reduce fuel consumption The combination of days-at-sea regulations, high oil prices, and the decreasing TAC for plaice and the relatively stable TAC for sole, appear to have induced a more southern fishing pattern in the North Sea. This concentration of fishing effort results in increased discarding of juvenile plaice that are mainly distributed in those areas. This process could be aggravated by movement of juvenile plaice to deeper waters in recent years where they become more susceptible to the fishery. Also the lpue data show a slower recovery of stock size in the southern regions that may be caused by higher fishing effort in the more coastal regions. The assessment is considered to be highly uncertain, partly because discards form a substantial part of the total catch and cannot be well estimated from the low number of annual sampling trips, but most importantly due to the large differences in abundance observed in the different regions of the North Sea. The TAC constraint in the EU management plan is designed to allow for the uncertainty in the assessment. ICES has developed a generic approach to evaluate whether new survey information that becomes available in September forms a basis to update the advice. If this is the case, ICES will publish new advice in November Management plan evaluations In the 2008 evaluation of the management plan for plaice a number shortcomings were observed: - lack of robustness to the starting values of population abundance; - systematic over-estimation of historic landings; - under-estimation of bias and variance in the assessment model. Therefore ICES cannot presently conclude on the precautionary nature of the management plan for plaice. To be able to do so, the causes for the observed lack of robustness to the starting values need to be clarified. Additional evaluations should take into account various sources of assessment errors and include uncertainties associated with possible changes in discard practices. Uncertainties associated with the recent observed changes in the spatial distribution pattern of the stock and fishery, and the fact that some surveys and fishing fleets used in the assessment cover different parts of the stock distribution area need to be taken into account as well. Impacts of fisheries on the ecosystems Currently the mixed plaice and sole fishery is dominated by bottom trawls, with bycatch of both commercial and noncommercial species and a physical impact on the seabed. Bottom trawling reduces biomass, production, and species richness. For the North Sea, an ecosystem model showed that the bottom trawl fleet reduced benthic biomass and production by 56% and 21%, respectively, compared with an un-fished situation (Hiddink et al., 2006; Hinz et al., 2008). Chronic fishing has caused a shift from communities dominated by relatively sessile, emergent, high biomass species to communities dominated by infaunal, smaller-bodied fauna (Kaiser et al., 2000). 74 ICES Advice 2009, Book 6

79 Within species, the size selectivity may lead to a shift in the age and size at maturation. For example, plaice and sole become mature at younger ages and at smaller sizes in recent years than in the past. There is a risk that this shift is a genetic fisheries-induced change (Grift et al., 2004; Mollet et al., 2007). Factors affecting the fisheries and the stock Regulations and their effects The Dutch beam trawl fleet has reduced its number of vessels and technical management measures caused a shift towards two categories of vessels: 2000 HP (the maximum engine power allowed) and 300 HP. The 300 HP vessels are allowed to fish within the 12-nautical mile coastal zone and in the plaice box. A substantial number of the Dutch vessels have been replaced by vessels registered in other countries (England, Scotland, Germany, and Belgium). Approximately 85% of plaice landings from the UK (England and Scotland) is landed into the Netherlands by Dutch vessels fishing on the UK register. The technical efficiency has increased by about 1.6% per year in the plaice fishery since 1990, which could have counteracted part of the overall decrease in effort (Rijnsdorp et al., 2006). The overall capacity and effort of North Sea beam trawl vessels appears to have decreased since This decrease has continued in 2009 with the decommissioning of 25 Dutch trawl vessels. The minimum landing size of North Sea plaice is 27 cm. This minimum landing size results in high discarding levels in the mixed flatfish fishery with beam and bottom trawls using 80 mm mesh size. The Plaice Box is a closed area along the continental coast that has been introduced in The area has been closed all year round since The closed area applies to vessels using towed gears, but vessels smaller than 300 HP are exempted from the regulation. An STECF evaluation of the plaice box has indicated that: From trends observed it was inferred that the Plaice Box has likely had a positive effect on the recruitment of plaice but that its overall effect has decreased since it was established. There are two reasons to assume that the Plaice Box has a positive effect on the recruitment of plaice: 1) At present, the Plaice Box still protects the majority of undersized plaice. Approximately 70% of the undersized plaice are found in the Plaice Box and Wadden Sea. Despite the changed distribution, densities of juvenile plaice inside the Box are still higher than outside; 2) In the 80 mm fishery, discard percentages in the Box are higher than outside. Because more than 90% of the plaice caught in the 80 mm fishery in the Box are discarded, any reduction in this fishery would reduce discard mortality. (Grift et al., 2004). Changes in fishing technology and fishing patterns Due to a range of factors such as effort limitations, increases in fuel prices, and disproportionate changes in the TACs for the two main target species plaice and sole, the fishing effort of the major fleets has concentrated in the southern part of the North Sea. This is the area where many juvenile fish are found. In addition, juvenile plaice has shown a more offshore distribution in recent years. The combination of a change in fishing pattern and the spatial distribution of juvenile plaice has lead to an increase in discarding of plaice. Impacts of the environment on the fish stock Adult North Sea plaice have an annual migration cycle between spawning and feeding grounds. The spawning grounds are located in the central and southern North Sea, overlapping with the distribution area of sole. The feeding grounds are located more northerly than the sole distribution areas. Juvenile stages are concentrated in shallow inshore waters and move gradually offshore as they become larger. The nursery areas on the eastern side of the North Sea contribute most of the total recruitment. Sub-populations have strong homing behavior to specified spawning grounds and rather low mixing rate with other sub-populations during the feeding season. Juvenile plaice have been distributed more offshore in recent years. Surveys in the Wadden Sea have shown that 1- group plaice is almost absent from the area where it was very abundant in earlier years. This could be linked to environmental changes in the productivity or changes in the temperature of the southern North Sea, but these links have not been shown conclusively. The distribution shift of plaice may be the cause for the different abundance estimates in the different tuning series used in the assessment. ICES Advice 2009, Book 6 75

80 Scientific basis Data and methods The stock assessment is based on an age-based model (XSA) using landings and discards, calibrated with three survey indices: BTS-Tridens, BTS-Isis, and SNS. A Statistical Catch at Age model (Aarts & Poos 2009) has been run in parallel to the current XSA. The SCA model estimates similar stock trends compared to the XSA. Discards estimates are based on Dutch, UK, German, and Danish samples from observer programmes, on different fleet segments. For the years prior to 2000, discards were reconstructed based on a model-based analysis of growth, selectivity of the 80 mm beam trawl gear, and the availability of undersized plaice on the fishing grounds. Information from the fishing industry A self-sampling programme by the Dutch beam trawl fleet has been in place since This sampling effort indicates spatial and temporal trends in discarding; higher discards are observed in coastal regions and late summer. However, the self sampling gives overall lower estimates of discarding. This discrepancy is caused by differences in the implementations of different sampling methods (Aarts and van Helmond, 2009). The North Sea Fishers' Survey for 2008 resulted in a total of 303 responses. The large vessel group was dominated by respondents fishing with beam trawls (70%), stating that the plaice abundance is more and much more. This is consistent with the trends in the assessment. In terms of discarding, the modal response was that there was no change in discarding. Uncertainties in assessment and forecast The estimated increase in SSB is due to an increase in plaice observed in the survey in the north-western part of the North Sea. The surveys in the south-eastern part indicate that the stock has increased less. The different survey tuning series in different areas of the North Sea indicate different trends in the most recent development of the stock. This gives problems in the interpretation of the signals; this has resulted in a relatively strong retrospective pattern, with this years assessment estimating much higher SSBs and lower fishing mortalities for the most recent years. Discards form a substantial part of the total catch and cannot be well estimated from the limited number of sampling trips. The different trends in abundance in the two areas may indicate a change in distribution of older plaice, as has also been observed for juvenile plaice. However, the difference in distribution may also be explained by different exploitation rates in the two areas, with individual plaice in the more northern part susceptible to much lower fishing mortality. Comparison with previous assessment and advice In 2008 the SSB for 2008 was estimated at 265 kt, while this assessment estimates the SSB for that same year (2008) at 345 kt. Similarly, the F in 2007 was estimated at 0.39, while this year assessment estimates F in 2007 at 031. Last year ICES advised according to management plan aiming at a reduction in F of 10%. For this year, the basis of the advice in 2010 is to apply the EU management plan, corresponding to a 15% constraint on TAC increase. Sources of information Report of the Working Group on the Assessment of Demersal Stocks in the North Sea and Skagerrak, 6-12 May 2009 (ICES CM 2009/ACFM:10). Aarts, G. M., and van Helmond, A. T. M Discard sampling of plaice (Pleuronectes platessa) and cod (Gadus morhua) in the North Sea by the Dutch demersal fleet from 2004 to IJmuiden, IMARES, Report C120/07, p. 42. Aarts, G.M.; Poos, J.J. (2009). Comprehensive discard reconstruction and abundance estimation using flexible selectivity functions. ICES Journal of Marine Science 66 (4). - p Grift, R. E., Tulp, I., Clarke, L., Damm, U., McLay, A., Reeves, S., Vigneau, J., and Weber, W Assessment of the ecological effects of the Plaice Box. Report of the European Commission Expert Working Group to evaluate the Shetland and Plaice boxes. Brussels. 121 pp. Hiddink, J. G., Jennings, S., Kaiser, M. J., Queirós, A. M., Duplisea, D. E, and Piet, G. J Cumulative impacts of seabed trawl disturbance on benthic biomass, production, and species richness in different habitats. Canadian Journal of Fisheries and Aquatic Sciences, 63: Hinz, H., Hiddink, J. G., Forde, J., and Kaiser, M. J Large-scale responses of nematode communities to chronic otter-trawl disturbance. Canadian Journal of Fisheries and Aquatic Sciences, 65: ICES Advice 2009, Book 6

81 Kaiser, M. J., Ramsay, K., Richardson, C. A., Spence, F. E., and Brand, A. R Chronic fishing disturbance has changed shelf sea benthic community structure. Journal of Animal Ecology, 69: Mollet, F. M., Kraak, S. B. M., and Rijnsdorp, A. D Fisheries-induced evolutionary changes in maturation reaction norms in North Sea sole Solea solea. Marine Ecology Progress Series, 351: Rijnsdorp, A. D., Daan, N., and Dekker, W Partial fishing mortality per fishing trip: a useful indicator of effective fishing effort in mixed demersal fisheries. ICES Journal of Marine Science, 63: Table Plaice in Subarea IV (North Sea). Single stock exploitation boundaries (advice), management and landings. Single-stock exploitation boundaries Predicted Predicted catch catch corresponding corresponding to single-stock to advice boundaries Agreed Official ICES Year ICES Advice TAC landings landings 1987 F<F(84); TAC % of F(85); TAC Reduce F; Buffer SSB < status quo F; TAC No increase in F; TAC No long-term gains in increasing F No long-term gains in increasing F No long-term gains in increasing F Significant reduction in F Reduction in F of 40% Reduction in F of 20% Fish at F= Fish at F= Fish at F= Fish at F= F<F pa < Fish at F= Recovery plan Rebuild the SSB above B pa in Rebuild the SSB above B pa in Rebuild the SSB above B pa in 2008 < Rebuild the SSB above B pa in 2009 < Limit total landings to t < Limit total landings to t < Weights in 000t. 1) Catch at status quo F. 2) Catch at 20% reduction in F. 3) After revision from t. 4) Landings. ICES Advice 2009, Book 6 77

82 Figure Plaice in Subarea IV (North Sea). Summary of stock assessment. Top left: Total catches (solid black line) landings (dotted line) and discards (dashed line); Top right: total fishing mortality (blue line), and fishing mortality of landings (red line); Bottom right: fishing mortality of discards. 78 ICES Advice 2009, Book 6

83 Figure Plaice in Subarea IV (North Sea). SSB and recruitment, predicted values are shaded. ICES Advice 2009, Book 6 79

84 Stock - Recruitment 5 Recruitment (age 1) in billions SSB-Rec. Blim Bpa SSB in 1000 t Yield and Spawning Stock Biomass per Recruit Yield (dashed line) SSB (line) Fishing Mortality (ages 2-6) SSB in 1000 t Precautionary Approach Plot Period Fishing Mortality (ages 2-6) F-SSB 2008 Flim Fpa Blim Bpa Figure Plaice in Subarea IV (North Sea). Yield per recruit analysis and stock recruitment plot. 80 ICES Advice 2009, Book 6

85 Figure Plaice in Subarea IV (North Sea). Results of the North Sea Commission fishers survey Plaice Subarea IV (North Sea) SSB ('000 tonnes) Fishing mortality: Millions Recruitment. Age: Figure Plaice in Subarea IV (North Sea). Comparison of current assessment with previous assessments. Note the change in assessment methodology from 2004 onwards. ICES Advice 2009, Book 6 81

86 Table Plaice in Subarea IV (North Sea). Nominal landings by country and area (tonnes). YEAR Belgium Denmark France Germany Netherlands Norway Sweden UK Others Total Unallocated WG estimate TAC * ICES Advice 2009, Book 6

87 Table Plaice in Subarea IV (North Sea). Summary of stock assessment. Recruitment Age 1 (thousands) SSB Catch Landings Discards Mean F Landings ages 2-6 Mean F Discards ages 2-3 Mean F (tonnes) (tonnes) (tonnes) (tonnes) Total ages * * Recruitment GM ( ). ICES Advice 2009, Book 6 83

88 6.4.7 Appendix Extract from Council Regulation (EC) No 676/2007 of 11 June 2007 establishing a multiannual plan for fisheries exploiting stocks of plaice and sole in the North Sea: Article 7 Procedure for setting the TAC for plaice: 1) The Council shall adopt the TAC for plaice at that level of catches which, according to a scientific evaluation carried out by STECF is the higher of: a) that TAC the application of which will result in a 10 % reduction in the fishing mortality rate in its year of application compared to the fishing mortality rate estimated for the preceding year; b) that TAC the application of which will result in the level of fishing mortality rate of 0.3 on ages two to six years in its year of application. 2) Where application of paragraph 1 would result in a TAC which exceeds the TAC of the preceding year by more than 15 %, the Council shall adopt a TAC which is 15 % greater than the TAC of that year. 3) Where application of paragraph 1 would result in a TAC which is more than 15 % less than the TAC of the preceding year, the Council shall adopt a TAC which is 15 % less than the TAC of that year. 84 ICES Advice 2009, Book 6

89 6.4.8 Plaice in Division VIId (Eastern Channel) State of the stock Spawning biomass in relation to precautionary limits Fishing mortality in relation to precautionary limits Fishing mortality in relation to high long-term yield Fishing mortality in relation to agreed management targets Unknown Unknown Unknown Unknown Comment The assessment is indicative of trends only. The SSB trends suggest that the spawning-stock biomass has declined through the last 15 years to a stable historical low level. The current level of SSB is low. F varies without trend around the long-term average. Recruitment in 2006 and 2007 have been above average. Management objectives There are no explicit management objectives for this stock. Reference points Precautionary approach Type Value Technical basis B lim 5,600 t B loss (~1995) B pa 8,000 t 1.4 B lim F lim 0.54 F loss (~1995) F pa th percentile of F loss ; long-term SSB >B pa and P(SSB MT <B pa ) < 10%. Targets F y Not defined (unchanged since 1998) Single-stock exploitation boundaries In the absence of a short-term forecast, ICES advises on the basis of exploitation boundaries in relation to precautionary considerations that landings in 2010 should not increase above the average of landings from the last three years ( ), corresponding to landings less than t. Management considerations There is a limited directed fishery on plaice at the beginning of the year on the spawning grounds. This fishery catches plaice that originates from both the North Sea and VIId components. However, plaice is mainly taken as bycatch in the demersal fisheries, especially in the fisheries targeting sole. Due to the minimum mesh size (80 mm) in the mixed beam trawl fishery, a large number of undersized plaice are discarded. The 80-mm mesh size is not matched to the minimum landing size of plaice (27 cm). Measures taken specifically directed at sole fisheries will also impact the plaice fisheries. Following the EU Commission consultation paper on TACs for 2010 (COM(2009) 224, 12 May 2009) this stock would be categorised based on the average of SSB in the last 2 years compared to the average of the 3 preceding years. For this stock only relative measures of stock biomass are available but these show a reduction of 3%, resulting in an unchanged TAC. ICES has not evaluated this rule in relation to the precautionary approach. Factors affecting the fisheries and the stock The effects of regulations In previous years, effort from the beam trawl fleet has not been restricted. The new EU Council Regulation (EC) N 43/2009 does not reduce the effort for this fleet. ICES Advice 2009, Book 6 85

90 Scientific basis Data and methods The XSA exploratory assessment is valid for trends only and is based on reported landings data, three commercial cpue indices, and three survey indices. Time-series of discard data are not available, but observations from all fisheries from 2003 indicate that discards are high. Uncertainties in assessment and forecast There is uncertainty about the stock structure. Historical tagging information shows that around 40% of the juvenile plaice in Division VIId come from nursery grounds in the North Sea, while the Eastern Channel supplies very few recruits to the North Sea. Similarly, around 20% of the recruits in Division VIIe come from VIId, while VIId does not receive significant numbers of juvenile from VIIe. There is also an adult migration between the North Sea and the Channel 20 30% of the plaice caught in the winter in VIId were from migratory North Sea fish. The available information also suggests that plaice may migrate from the VIIe into the VIId and the North Sea after spawning. Lack of discarding information also adds to the uncertainty. Routine discard sampling began in 2003 following the introduction of the EU Data Collection Regulations and indicates percentages of discards up to 50% in number, depending on the trip and on fishing practices. However, the time-series of discards is not yet long enough to be used in an analytical assessment. Comparison with previous assessment and advice The assessment was considered unreliable due to problems in stock structure identity and the absence of discards in the assessment. This year s advice is similar to last year s advice which was not to exceed average recent landings. Source of information Report of the Working Group on the Assessment of Demersal Stocks in the North Sea and Skagerrak, 6-12 May 2009 (ICES CM 2009/ACOM:10). 86 ICES Advice 2009, Book 6

91 Table Plaice in Division VIId. Single stock exploitation boundaries (advice), management and landings. Year ICES Advice (Single-stock Exploitation Boundaries since 2004) Predicted catch corresp. to advice Agreed TAC 1 Official landings ICES landings 1987 Precautionary TAC Precautionary TAC No increase in effort No increase in F; TAC TAC Status quo F gives mean SSB Within safe biological limits No long-term gains in increased F No increase in F No long-term gains in increasing F No advice Reduce F in 98 by 30% from Fishing at F pa Fishing at F pa Fishing at <F pa < Fishing at <F pa < Fishing at <F pa < *) Fishing at <F pa < *) Fishing at <F pa < No effort increase *) Average landings *) < Average landings *) < Average landings *) < Average landings *) <3.5 Weights in 000 t. 1 TACs for Divisions VIId,e. 2 For France Division VIId landings are estimated by ICES from the combined VIId,e landings. 3 Catch at status quo F. *) Single-stock boundary and the exploitation of this stock should be conducted in the context of mixed fisheries. ICES Advice 2009, Book 6 87

92 Fishing Mortality F(ages 2-6) F Recruitment (age 1) Recruitment Spawning Stock Biomass SSB SSB Figure Plaice in Division VIId (Eastern Channel). Landings (in 000 t), fishing mortality, recruitment, and SSB. Indicative of trends only. ICES Advice 2009, Book 6

93 Table Plaice in Division VIId. Catches/landings by country and by area (in '000 t). Year Belgium Denmark France UK(E+W) Others Total Un- Total as reported allocated used by WG (1) (2) (2) (2) (2) (2) (2) (1) (1) (1) (2) (2) (2) (23) (23) (3) (4) Estimated by the working group from combined Division VIId+e 2 Includes Division VIIe 3 Provisional 4 Data provided to the WG but not officially provided to ICES ICES Advice 2009, Book 6 89

94 6.4.9 Sole in Division IIIa (Skagerrak and Kattegat) State of the stock Spawning biomass in relation to precautionary limits Full reproductive capacity Fishing mortality in relation to precautionary limits Fishing mortality in relation to high longterm yield Harvested sustainably Appropriate NA Fishing mortality in relation to agreed management target Comment Based on the most recent estimates of SSB (in 2009) and F (in 2008), ICES classifies the stock as having full reproductive capacity and being harvested sustainably. SSB has decreased since 2005 but is still well above B pa. Fishing mortality has increased from 0.22 in 2007 to 0.28 in Recruitment has been below average in recent 4 years. Management objectives There are no management objectives for this stock. Reference points Precautionary approach Type Value Technical basis B lim 770 t B pa *exp(-1.645*0.2) B pa 1060 t MBAL F lim 0.47 F med 98 excluding the abnormal years around 1990 F pa 0.30 consistent with F lim Targets F y not defined (unchanged since 1999) Yield and spawning biomass per Recruit F-reference points: Fish Mort Yield/R SSB/R Ages 4-8 Average last 3 years F max * F F med * F max not well defined Candidates for reference points which are consistent with high long-term yields and a low risk of depleting the productive potential are in the range of F 0.1 to F pa. Single-stock exploitation boundaries ICES advises on the basis of exploitation boundaries in relation to precautionary limits that fishing mortality in 2010 should be kept below F pa, corresponding to landings of less than 620 t. 90 ICES Advice 2009, Book 6

95 Short-term implications Basis: F(2009) = F sq = mean F(06 08) rescaled to the last year = 0.28; R94 06 = GM = 3.1 million; SSB(2009) =2.4; SSB(2010) = 2.3; landings (2009) = Rationale Landings (2010) Basis F(2010) SSB(2011) %SSB change 1 %TAC change 2 Zero catch 0 F= % -100% Status quo 0.58 F sq % -28% 0.07 F pa * % -91% 0.17 F pa * % -79% 0.33 F pa * % -59% 0.58 F pa *0.73 = F sq % -40% 0.56 F pa * % -30% Precautionary limits 0.62 F pa = F sq * % -23% 0.67 F pa * % -16% 0.75 F pa * % -6% 0.87 F pa * % 9% 0.99 F pa * % 23% All weights in thousand tonnes. Shaded scenarios are not considered consistent with the precautionary approach. 1) SSB 2011 relative to SSB ) Landings 2010 relative to TAC Management considerations The fishery for sole in the adjacent Belt Sea has increased in recent years with landings of about 15-20% of the landings in Kattegat and Skagerrak. The TAC applies to all of the Divisions IIIa, b, c, and d (i.e. the Skagerrak, the Kattegat, and both the Western and the Eastern Baltic) although the advice is based on the state of the stock in Division IIIa only. The stock structure must be investigated to determine to what extent sole in the Belt Sea belong to the same stock unit as sole in Kattegat/Skagerrak and consequently whether they should be managed together or separately. During the period there was considerable misreporting due to limiting TACs and weekly quota. Since mid- 2005, the increase in TAC and improved control appears to have resulted in negligible misreporting. Sole is taken in a directed trawl fishery with bycatch of Nephrops and cod. Cod in the Kattegat is considered to be severely depleted. Also, sole is taken as bycatch in the Nephrops trawl fishery. There is a directed gillnet fishery for sole. Regulations and their effects The Danish fishery has in the past been regulated by half-monthly quotas which depended on vessel length and varied over the year. From 2007 a vessel quota share system (VQS) was put in force, allowing fishers to trade quotas and to decide when to fish them. The VQS was fully implemented during late The logbook data do not indicate any effects of the VQS on seasonal/spatial effort distribution. The management area includes Division IIIa plus the Western Baltic (Subdivisions 22 24). Danish vessel quota shares cover the management area and there is therefore no incentive to misreport sole taken in Division IIIa into the Western Baltic. Factors affecting the fisheries and the stock Changes in fishing technology and fishing patterns There are no major changes in the sole-directed fishery in recent years. Changes in the regulations for the Nephrops fishery, with the introduction of a sorting grid system in the trawls, may have resulted in smaller bycatch and improved selectivity on sole. Since 1 February 2008 exit square mesh panels have been mandatory in the trawl fishery to prevent by-catches of cod. This device is not expected to influence the sole catches. ICES Advice 2009, Book 6 91

96 Impact of the environment on the fish stock The stock is probably influenced by both temperature and salinity because it is located near the species physiological limits for both of these factors. Scientific basis Data and methods The analytical XSA assessment includes cpue data from three commercial tuning series (reference fleets) and one scientific survey series. Discarding is not assumed to occur to any extent of importance to the assessment and is not included. During the period there was considerable misreporting due to limiting TACs and weekly quota which were included in the assessment. Since mid-2005, the increase in TAC and improved control are believed to have resulted in insignificant misreporting. Information from the fishing industry Collaboration between the Danish Fishers Organization and DTU Aqua was initiated in 2004 to establish a database with data from private logbooks. Haul-specific data from six trawlers and three gillnetters covering the time period 1987 to 2008 were used in the assessment. However, the gillnetter information was not available in Uncertainties in assessment and forecast The assessment is considered uncertain; in recent years there is a tendency to overestimate SSB. There is a need for fishery-independent data as the current survey does not target sole. A sole-directed research survey was initiated in 2004, and the time-series of catch rates will be considered in 2010 when it is sufficiently long and when the survey has been evaluated as an abundance index. If the share of catches in the Belt Sea remains important and if the population, in that area belongs to the IIIa stock the basis for the assessment and advice should include catches from the Belt Sea. Comparison with previous assessment and advice The present assessment has revised the perception of the recent levels of SSB and F as SSB in 2008 has been overestimated by 30%, while estimates of F in 2007 has been underestimated by 5%. (Figure ). The basis for present advice is the same as last year. Source of information Report of the Baltic Fisheries Assessment Working Group. Copenhagen, April 2009 (ICES CM 2009/ACOM:06). 92 ICES Advice 2009, Book 6

97 Table Sole in Division IIIa. Single stock exploitation boundaries (advice), management and landings. Year ICES Advice Single-stock exploitation boundaries Predicted catch corresp. to advice Weights in 000 t. 1) Uncertain. 2) TAC applies to Division IIIa and the EC waters of Divisions IIIb and IIIc, d. Predicted catch corresp. to single-stock exploitation boundaries Agreed TAC 2 ICES Landings TAC < Precautionary TAC TAC TAC TAC at recent catch levels No advice due to uncertain catches No advice No advice No advice No advice No increase in F No increase in F No increase in F F below F pa F below F pa F below F pa No increase in F F below F pa Limit catches to average keep F below F pa keep F below F pa keep F below F pa 0.62 ICES Advice 2009, Book 6 93

98 Landings in 1000 t Landings Fishing Mortality F(ages 4-8) F Flim Fpa Recruitment in millions Recruitment (age 2) SSB in 1000 t Spawning Stock Biomass SSB Blim Bpa Figure Sole in Division IIIa. Landings, fishing mortality, recruitment, and SSB. Predicted values are shaded. 94 ICES Advice 2009, Book 6

99 Recruitment (age 2) in millions Stock - Recruitment SSB in 1000 t SSB-Rec. Blim Bpa Yield (dashed line) Yield and Spawning Stock Biomass per Recruit SSB (line) Fishing Mortality (ages 4-8) Precautionary Approach Plot Period SSB in 1000 t Fishing Mortality (ages 4-8) F-SSB 2008 Flim Fpa Blim Bpa Figure Sole in Division IIIa. Stock recruitment, yield, and precautionary approach. ICES Advice 2009, Book 6 95

100 6 5 SSB ('000 tonnes) Fishing mortality: Millions Recruitment. Age: Figure Sole in Division IIIa. Historical performance of the assessments. Note: some of the earlier assessments were considered valid for trends only. 96 ICES Advice 2009, Book 6

101 Table Sole in Division IIIa. Catches (tonnes) in the Kattegat and Skagerrak Official statistics and Working Group corrections. For Sweden there is no information Year Denmark Sweden Germany Belgium Netherlands Working Group Total Kattegat Skagerrak Skag+Kat Kat+Skag Skagerrak Skagerrak Corrections Norway Considerable non-reporting assumed for the period Catches from Skagerrak were reduced by these amounts because of misreporting from the North Sea. The subtracted amount has been added to the North Sea sole catches. Total landings for these years in IIIA has been reduced by the amount of misreporting. 3 Assuming misreporting rates at 50, 100, 100, and 20% in , respectively. ICES Advice 2009, Book 6 97

102 Table Sole in Division IIIa. Summary of the assessment. Year Recruitment SSB Landings Mean F Age 1 Ages 4-8 thousands tonnes tonnes * 2370 Average * Recruitment in 2009 is Geometric Mean ( ). 98 ICES Advice 2009, Book 6

103 Sole in Subarea IV (North Sea) State of the stock Spawning biomass in relation to precautionary limits Fishing mortality in relation to precautionary limits Fishing mortality in relation to high longterm yield Fishing mortality in relation to agreed target Comment Full reproductive capacity Harvested sustainably Appropriate Above target Based on the most recent estimate of SSB (in 2009) and fishing mortality (in 2008), ICES classifies the stock as having full reproductive capacity and is being harvested sustainably. SSB has fluctuated around the precautionary reference points for the last decade, but has increased since 2008 owing to a large incoming 2005 year class and reduced fishing mortality. Fishing mortality has shown a declining trend since 1995 and is currently estimated to be below F pa. The assessment suggests that the 2006 year class was below average, and 2007 average. Management objectives The EC has adopted a management plan for flatfish in the North Sea in June 2007 (Council Regulation (EC) No. 676/2007, see Annex). This plan has two stages. The first stage aims at an annual 10% reduction of fishing mortality in relation to the fishing mortality estimated for the preceding year until an F of 0.2 is reached, with a maximum change in TAC of 15% until the precautionary reference points are reached for both sole and plaice for two successive years. ICES interprets the F for the preceding year as the estimate of F for the year in which the assessment is carried out. The basis for this F estimate in the preceding year will be a constant application of the procedure used by ICES in In the second stage, the management plan aims for exploitation at F = 0.2. ICES has evaluated the long-term management plan and concluded that it leads on average to a low risk of B < B lim within the next 10 years. ICES concludes that for sole the management plan can be provisionally accepted as precautionary. According to the evaluation the agreed management plan can be provisionally accepted as precautionary for sole and could be used as a basis for the management of the stock in the short term. Additional evaluations of the management plan are necessary to take into account retrospective bias of the assessment and the sporadic nature of recruitment. Reference points Type Value Technical basis B lim 25,000 t B loss Precautionary B pa 35,000 t B pa 1.4 *B lim approach F lim Not defined F pa 0.40 F pa = 0.4 implies B eq > B pa and P(SSB MT < B pa ) < 10%. Targets F mgt 0.2 EU management plan (unchanged since 1998, target added in 2008) Yield and spawning biomass per Recruit F-reference points (2009): Fish Mort Yield/R SSB/R Ages 2 6 Average last 3 years F max * F F med *Poorly defined Candidates for reference points consistent with high long-term yields and a low risk of depleting the productive potential of the stock are in the range of F 0.1 F pa. ICES Advice 2009, Book 6 99

104 Single-stock exploitation boundaries Considering the options below, ICES advises on the basis of exploitation boundaries in relation to the agreed management plan that landings should be less that t in Exploitation boundaries in relation to the agreed management plan According to the management plan adopted by the EC in 2007, fishing mortality in 2010 should be reduced by 10% compared to the fishing mortality estimated for the preceding year (F2008=F2009=0.34) with the constraints that the TAC should not be changed by more than 15%. A 10% reduction in fishing mortality corresponds to an F of and landings of t in 2010 which is within the 15% change (TAC 2009=14 000t). Exploitation boundaries in relation to high long-term yield, low risk of depletion of production potential and considering ecosystem effects The current fishing mortality is within the range that is expected to lead to high long-term yields and low risk to stock depletion. Exploitation boundaries in relation to precautionary limits The fishing mortality in 2010 should be no more than F pa, corresponding to landings of less than t.. Short-term implications Outlook for 2010 Basis: F(2009) = F sq = mean F( ) scaled to 2008 = 0.34 ; R(2009) = GM ( ) = mln; SSB(2010) = ; landings (2009) = Rationale Landings F SSB %SSB %TAC Basis (2010) (2010) (2011) change 1) change 2) Zero catch 0 F= % -100% High long-term yield 5.6 F % -60% Management plan 14.1 Fsq* % +1% 4.4 Fsq* % -69% Status quo 8.4 Fsq* % -40% 9.8 Fsq* % -30% 11.9 Fsq* % -15% 15.5 Fsq* % +10% 16.1 Fsq* % 17.8 Fsq*1.18 = Fpa % +27% 18.6 Fsq* % +33% 21.4 Fsq* % +53% 24 Fsq* % +72% 26.5 Fsq* % +89% Weights in 000 t. Shaded scenarios are not considered consistent with the precautionary approach. 1) SSB(2011) relative to SSB(2010). 2) Calculated landings (2010) relative to TAC 2009 ( t). Management considerations Sole are mainly caught in a mixed beam trawl fishery with plaice and other flatfish using 80 mm mesh in the southern North Sea. The minimum mesh size in the mixed beam trawl fishery in the southern North Sea means that large numbers of undersized plaice and cod are discarded. There are indications that in recent years sole discarding has taken place. Measures to reduce discarding in the mixed beam trawl fishery would greatly benefit these stocks. An increase in the minimum landing size of sole could provide an incentive to fish with larger mesh sizes and would therefore mean a reduction in the discarding of plaice. The minimum landing size of North Sea sole is 24 cm. An increased mesh size in the fishery would reduce the catch of undersized plaice and cod, but would also result in a short-term loss of marketable sole. 100 ICES Advice 2009, Book 6

105 For two succesive years, the stock has been classified within safe precautionary bounderies and thus fullfilled the 1 st phase of the management plan. The increase in SSB is mainly achieved by the strong 2005 year class. The main explanation for the reduction of fishing mortality seems to be a proper implementation of the current management plan complemented with a reduction of capacity in the beam trawl fleet and a limitation of fishing effort. Also high fuel prices have contributed to the decrease in fishing mortality. The peaks in the historical time-series of SSB of North Sea sole correspond with the occasional occurrence of strong year classes. Due to a high fishing mortality the SSB has declined during the nineties. The fishery opportunities and SSB are now dependent on incoming year classes and can therefore fluctuate considerably between years. The SSB and landings in recent years have been dominated by the 2001 and 2005 year classes. The predicted SSB in 2011 is still largely dependent on the above-average recruitment of the 2005 year class. ICES has developed a generic approach to evaluate whether new survey information that becomes available in September forms a basis to update the advice. If this is the case, ICES will publish new advice in November Management plan evaluation According to evaluation of the agreed management plan it can be provisionally accepted as precautionary for sole. Estimations of sole stock status appear to have a retrospective under-estimation of fishing mortality and over-estimation of SSB, which have resulted in forecast bias. The probability of successfully attaining the objectives of the first stage of the management plan is dependent on the assumption of a stock recruitment relationship, which is not well founded. The dynamics of the stock is driven by the sporadic strong year classes that lead to wide fluctuations in the SSB. Additional evaluations of the management plan are necessary to take into account retrospective bias of the assessment and the nature of recruitment to conclude on the precautionary nature of the plan in the long term. Impacts of fisheries on the ecosystem Currently the mixed plaice and sole fishery is dominated by bottom trawls, with bycatch of both commercial and noncommercial species and with physical impact on the seabed. Bottom trawling reduces biomass, production, and species richness. For the North Sea, an ecosystem model showed that the bottom trawl fleet reduced benthic biomass and production by 56% and 21%, respectively, compared with an un-fished situation (Hiddink et al., 2006; Hinz et al., 2008). Chronic fishing has caused a shift from communities dominated by relatively sessile, emergent, high biomass species to communities dominated by infaunal, smaller-bodied fauna (Kaiser et al., 2000). Within species, the size selectivity may lead to a shift in the age and size at maturation. For example, plaice and sole become mature at younger ages and at smaller sizes in recent years than in the past. There is a risk that this shift is a genetic fisheries-induced change (Grift et al., 2004; Mollet et al., 2007) Factors affecting the fisheries and the stock The effects of regulations Due to a range of factors such as TAC constraints on plaice, effort limitations, and increases in fuel prices, the fishing effort of the major fleets targeting sole has decreased since the mid-1990s and concentrated in the southern part of the North Sea. This is the area where a large part of the juvenile plaice in the North Sea is found. The combination of a change in fishing pattern and the spatial distribution of juvenile plaice has led to an apparent increase in discarding of plaice. The plaice box was established in 1989, and the area has been closed in all quarters since The closed area applies to vessels using towed gears, but vessels smaller than 300 HP are exempted from the regulation. The effectiveness of the plaice box has been evaluated by a STECF expert group which concluded that the proportion of undersized sole inside the plaice box did not change after the closure and remained stable at 60 70% (Grift et al., 2004). Changes in fishing technology and fishing patterns Due to a range of factors such as effort limitations, increases in fuel prices, and disproportionate changes in the TACs for the two main target species sole and plaice, the fishing effort of the major fleets has concentrated in the southern part of the North Sea. This is the area where many juvenile plaice are found. In addition, juvenile plaice has shown a more offshore distribution in recent years. The combination of a change in fishing pattern and the spatial distribution of juvenile plaice has lead to an increase in discarding of plaice. The technical efficiency has increased by about 2.8% per year in the sole fishery since 1990, which could have counteracted part of the decrease in effort (Rijnsdorp et al., 2006). ICES Advice 2009, Book 6 101

106 Impacts of the environment on the fish stocks There has been an overall increase in growth of North Sea sole, followed by a decline correlated with the temporal patterns in eutrophication, in particular the discharge of dissolved phosphates by the Rhine. The spatial distribution of juvenile and adult sole remains constant within the Plaice Box (Grift et al., 2004), following the removal of a large amount of effort. The proportion of undersized sole (<24 cm) did not change after closure and remained stable at a level of 60 70% (Grift et al., 2004). Different length groups showed different patterns in abundance. Sole of around 5 cm showed a decrease in abundance from 2000 onwards, while the groups of 10 and 15 cm seemed rather stable. The largest groups showed a declining trend in abundance, which had already set in years before the closure. Scientific basis Data and methods The stock assessment is based on an XSA assessment, calibrated with two survey indices and one commercial lpue index. Discards are not included in the assessment. Routine discard sampling since 2003 under the EU Data Collection Regulations indicates overall discarding of sole in the order of 10% in weight and discards are considered to be a minor bias to the assessment results. Uncertainties in assessment and forecast There are indications of recurring underestimation of fishing mortality and overestimation of abundance. A discrepancy between the trends in surveys and the commercial cpue is apparent in the the results of comparisons between survey and commercial time-series of information. The survey information indicates higer mortality rates and lower stock abundance, consistent with the more recent values to which the assessment estimates are revised each year. There are indications that discarding may have an impact on the assessment results Information from the fishing industry The North Sea Fisher s survey took place in A total of 195 responses were collected for sole. As in the 2007 survey, the beam trawl and gill net fishing groups indicated that sole were more abundant and the fishers felt that discarding had reduced slightly with respect to Of those that expressed an opinion on recruitment the majority considered it to be moderate or high. These observations are consistent with the assessment results. Comparison with previous assessment and advice The estimate of F for 2007 from the 2008 assessment was revised down by 5% in the 2009 assessment. The SSB estimate for 2007 increased 3% in the 2009 assessment. The revisions are different from retrospective bias in the assessment results previously. Fishing mortality in the intermediate year used in the 2009 forecast was the average F ( ) scaled to F (2008). The basis for this forecast is different from the previous forecasts, where the average F over the final 3 years was used to counteract the retrospective change from year to year. The advice this year is based on the EU management plan, similar to last year. Sources of information Report of the Working Group on the Assessment of Demersal Stocks in the North Sea and Skagerrak, 6-12 May 2009 (ICES CM 2009/ACOM:10). Grift, R. E., Tulp, I., Clarke, L., Damm, U., McLay, A., Reeves, S., Vigneau, J., and Weber, W Assessment of the ecological effects of the Plaice Box. Report of the European Commission Expert Working Group to evaluate the Shetland and Plaice boxes. Brussels. 121 pp. Hiddink, J. G., Jennings, S., Kaiser, M. J., Queirós, A. M., Duplisea, D. E, and Piet, G. J Cumulative impacts of seabed trawl disturbance on benthic biomass, production, and species richness in different habitats. Canadian Journal of Fisheries and Aquatic Sciences, 63: Hinz, H., Hiddink, J. G., Forde, J., and Kaiser, M. J Large-scale responses of nematode communities to chronic otter-trawl disturbance. Canadian Journal of Fisheries and Aquatic Sciences, 65: ICES Advice 2009, Book 6

107 Kaiser, M. J., Ramsay, K., Richardson, C. A., Spence, F. E., and Brand, A. R Chronic fishing disturbance has changed shelf sea benthic community structure. Journal of Animal Ecology, 69: Rijnsdorp, A. D., Daan, N., and Dekker, W Partial fishing mortality per fishing trip: a useful indicator of effective fishing effort in mixed demersal fisheries. ICES Journal of Marine Science, 63: Table Sole in Subarea IV (North Sea). Single stock exploitation boundaries (advice), management and landings. Year ICES Advice Single-stock exploitation boundaries Predicted catch corresponding to advice Predicted catch corresponding to single-stock Agreed TAC Official landings ICES landings 1987 Rebuild SSB to t; TAC Increase SSB towards t; TAC Increase SSB towards t; TAC % of F(88); TAC SSB> t ; TAC TAC no long-term gains in increased F no long-term gains in increased F no long-term gains in increased F Mixed fishery, link plaice advice <80% of F(95) % of F(96) F<F pa (80% of F(97)) F< F pa < F< F pa < F<0.37 < F< F pa < F< F pa 2 < F< F pa < Keep SSB above B pa < , SSB above B pa < SSB above 2008 B pa < Apply management plan < Apply management plan <14.1 Weights in 000 t. 1 Catch status quo F. 2 Single-stock boundary and the exploitation of this stock should be conducted in the context of mixed fisheries protecting stocks outside safe biological limits. ICES Advice 2009, Book 6 103

108 Figure Sole in Subarea IV (North Sea). Landings, fishing mortality, recruitment, and biomass (SSB). Predicted values are shaded. 104 ICES Advice 2009, Book 6

109 Stock - Recruitment 600 Recruitment (age 1) in millions SSB-Rec. Blim Bpa SSB in 1000 t Yield and Spawning Stock Biomass per Recruit Yield (dashed line) SSB (line) Fishing Mortality (ages 2-6) SSB in 1000 t Precautionary Approach Plot Period Fishing Mortality (ages 2-6) F-SSB 2008 Fpa Blim Bpa Figure Sole in Subarea IV (North Sea). Stock recruitment, yield, and precautionary approach. ICES Advice 2009, Book 6 105

110 Figure Sole in Subarea IV (North Sea). Results of the North Sea Commission fishers survey Sol e i n Sub-area I V ( N ort h Sea) SSB ('000 tonnes) Fishing mortality: Millions Recruitment. Age: Figure Sole in Subarea IV (North Sea). Historical performance of the assessments. 106 ICES Advice 2009, Book 6

111 Table Sole in Subarea IV (North Sea). Nominal landings and landings as estimated by the Working Group (tonnes). Year Belgium Denmark France Germany Netherlands UK Other Total Unallocated WG TAC (E/W/NI) countries reported landings Total ICES Advice 2009, Book 6 107

112 Table Sole in Subarea IV (North Sea). Summary of stock assessment. Year Recruitment SSB Landings Mean F Age 1 Ages 2-6 thousands tonnes tonnes * Average * GM ( ) 108 ICES Advice 2009, Book 6

113 Annex Extract from Council Regulation (EC) No 676/2007 of 11 June 2007 establishing a multiannual plan for fisheries exploiting stocks of plaice and sole in the North Sea Article 8 Procedure for setting the TAC for sole: 1) The Council shall adopt a TAC for sole at that level of catches which, according to a scientific evaluation carried out by STECF is the higher of: a) that TAC the application of which will result in the level of fishing mortality rate of 0,2 on ages two to six years in its year of application; b) that TAC the application of which will result in a 10 % reduction in the fishing mortality rate in its year of application compared to the fishing mortality rate estimated for the preceding year. 2) Where the application of paragraph 1 would result in a TAC which exceeds the TAC of the preceding year by more than 15 %, the Council shall adopt a TAC which is 15 % greater than the TAC of that year. 3) Where the application of paragraph 1 would result in a TAC which is more than 15 % less than the TAC of the preceding year, the Council shall adopt a TAC which is 15 % less than the TAC of that year. Under the consideration nr 3 in the Council Regulation (EC) No 676/2007 of 11 June 2007 establishing a multiannual plan for fisheries exploiting stocks of plaice and sole in the North Sea it is stated: The Scientific, Technical and Economic Committee for Fisheries (STECF) has advised that the precautionary biomass for the stock of sole in the North Sea should be tonnes. ICES Advice 2009, Book 6 109

114 Sole in Division VIId (Eastern Channel) State of the stock Spawning biomass in relation to precautionary limits Full reproductive capacity Fishing mortality in relation to precautionary limits Fishing mortality in relation to high longterm yield Increased risk Overfished NA Fishing mortality in relation to agreed management targets Comment Based on the most recent estimate of SSB (in 2009) and fishing mortality (in 2008), ICES classifies the stock as having full reproductive capacity and at risk of being harvested unsustainably. The spawning-stock biomass has been fluctuating around a mean of about t since 1982, and has been above B pa since The fishing mortality has decreased since 1999 and has been around F pa from 2001 until In the last 3 years fishing mortality has increased and fluctuated between F pa and F lim. The 2001, 2004 and 2005 year classes were the three highest since The 2007 year class is the weakest in the time-series. Management objectives No explicit management objectives are set for this stock. Reference points Precautionary approach Type Value Technical basis B lim Not defined Poor biological basis for definition B pa 8000 t This is the lowest observed biomass at which there is no indication of impaired recruitment. Smoothed B loss F lim 0.55 F loss, but poorly defined; analogy to North Sea and setting of 1.4 F pa = This is a fishing mortality at or above which the stock has shown continued decline. F pa 0.4 Between F med and 5th percentile of F loss ; SSB>B pa and probability (SSB mt <B pa ), 10%: 0.4. Targets F y Not defined (unchanged since 1998) Yield and spawning biomass per Recruit F-reference points (2009): Fish Mort Yield/R SSB/R Ages 3-8 Average last 3 years Fmax F Fmed Candidates for reference points which are consistent with high long-term yields and a low risk of depleting the productive potential of the stock are in the range of F 0.1 -F max. Single-stock exploitation boundaries Considering the options below, ICES advises on the basis of precautionary limits that fishing mortality in 2010 should be no more than F pa corresponding to landings of less than 3190 t in 2010 Exploitation boundaries in relation to high long-term yield, low risk of depletion of production potential, and considering ecosystem effects Fishing mortality in 2008 is estimated at 0.45, above the range that would lead to high long-term yields and low risk of stock depletion. 110 ICES Advice 2009, Book 6

115 Exploitation boundaries in relation to precautionary limits The fishing mortality in 2010 should be below F pa corresponding to landings less than 3190 t in 2010, which is expected to keep SSB above B pa in Short-term implications Outlook for 2010 Basis: F(2009) = Fsq = mean F(06-08) = 0.47; R(2009) = GM = 23.6 million; SSB(2009) = 10.6 ; SSB(2010) = 7.91; landings (2009) = 4.19 Rationale Landings %SSB %TAC (2010) 1) Basis F(2010) SSB(2011) change 2) Change 3) Zero catch 0.00 F= % -100% High long term yield 2.27 F(long term yield) % -57% 2.38 Fsq * % -55% 2.72 Fsq * % -49% 3.04 Fsq * % -42% Status quo 3.19 Fsq * % -40% 3.35 Fsq * % -36% 3.65 Fsq * % -31% 3.94 Fsq * % -25% 4.22 Fsq * % -20% 4.48 Fsq * % -15% Weights in '000 t. Shaded scenarios are considered not consistent with precautionary approach. 1) It is assumed that the TAC will be implemented and that the landings in 2010 therefore correspond to the TAC. 2) SSB 2011 relative to SSB ) Landings 2010 relative to TAC Management considerations Sole is mainly caught in beam trawl fisheries with plaice or in mixed demersal fisheries using otter trawls. There is also a directed fishery during parts of the year by inshore trawlers and netters on the English and French coasts. Due to the minimum mesh size (80 mm) in the mixed beam trawl fishery, a large number of (undersized) plaice are discarded. The 80 mm mesh size is not matched to the minimum landing size of plaice. Measures to reduce discarding of plaice in the sole fishery would greatly benefit the plaice stock and future yields. Mesh enlargement would reduce the catch of undersized plaice, but would also result in short-term loss of marketable sole. An increase in the minimum landing size of sole could provide an incentive to fish with larger mesh sizes and therefore mean a reduction in the discarding of plaice. Under-reporting of catches and misreporting of sole into Division VIId from Division VIIe is thought to be significant and should be avoided. This will also improve the quality of the assessment. Factors affecting the fisheries and the stock There are five main commercial fleets fishing for sole in Division VIId. Belgian and English offshore beam trawlers (> 300 HP) fish mainly for sole, but can switch to scallops or move to adjacent areas. French offshore trawlers target roundfish and take sole as bycatch. Numerous inshore vessels (under 10 m) on the English and French coasts target sole in the spring and autumn, using mainly fixed nets. The inshore vessels take half the reported landings and sole forms their main source of income. Effort from the beam trawl fleet can change considerably depending on whether the fleet moves to other areas or directs effort at other species such as scallops and cuttlefish. Regulations and their effects The minimum landing size for sole is 24 cm. Demersal gears are permitted to catch sole with mesh size 80 mm for beam and otter trawling. For static gear the minimum mesh size is 120 mm, with exceptions for trammelnets (100 mm) and static gear targeting red mullet and sea bass (90 mm). In previous years, effort from the beam trawl fleet has not been restricted. The new EU Council Regulation (EC) N 43/2009 does not reduce the effort for this fleet. ICES Advice 2009, Book 6 111

116 Changes in fishing technology and fishing patterns Effort for the Belgian beam trawl fleet increased to the highest level in This was mainly due to the unrestrictive days-at-sea EU regulation in ICES Subdivision VIId from 2006 until Impact of fisheries on the environment Currently the sole fishery is dominated by bottom trawls, with bycatch of both commercial (for instance plaice) and non-commercial species and physical impact on the seabed. Chronic fishing with bottom trawls has caused a shift from communities dominated by relatively sessile, emergent, high biomass species to communities dominated by infaunal, smaller-bodied fauna (Kaiser et al., 2000). Scientific basis Data and methods The XSA assessment, which was benchmarked in 2009, is based on landings data, two commercial cpue indices, and three research-vessel survey indices. Discards are not included in the assessment. Routine discard sampling since 2003 under the EU Data Collection Regulations indicates overall discarding of sole in the order of 5% in weight and discards are therefore considered to be a minor bias to the assessment results. Uncertainties in assessment and forecast Under-reporting from the inshore fleets and misreporting into Division VIId by beam trawlers fishing in VIIe is thought to be significant. Historical landings have been adjusted for misreporting between the Eastern and Western Channel since In recent years there have been substantial changes in the estimates of recruitment which impact on the forecast. Comparison with previous assessment and advice In 2009 the Young fish survey was separated into two components due to the cessation of the UK component in The current assessment has revised the value of SSB in 2007 and 2008 downward by 14% and 10% respectively (Figure ). The estimate of fishing mortality in 2007 was revised upwards by 26%. Past recruitment estimates were subject to considerable annual revision. The strong 2004 year class has been confirmed by the latest four assessments. The weak year class 2006 has been revised upward in this year s assessment by 78% and the assumed GM for the incoming 2007 year class in last year s assessment has now been revised downward by 62%.. The advice basis is the same as last year. The advice for 2010 is considerably lower than last year because of a downward revision of estimated stock size and poor incoming recruitment. Sources of information Report of the Working Group on the Assessment of Demersal Stocks in the North Sea and Skagerrak, 6-12 May 2009 (ICES CM 2009/ACOM:10). ICES Report of the Benchmark and Data Compilation Workshop for Flatfish (WKFLAT 2009), 6 13 February 2009, Copenhagen, Denmark. ICES CM 2009/ACOM:31. Kaiser, M. J., Ramsay, K., Richardson, C. A., Spence, F. E., and Brand, A. R Chronic fishing disturbance has changed shelf sea benthic community structure. Journal of Animal Ecology, 69: ICES Advice 2009, Book 6

117 Table Year ICES advice Sole in Division VIId (Eastern Channel), Single stock exploitation boundaries (advice), management and landings. Single-Stock Exploitation Boundaries Predicted catch corresp. to advice Predicted catch corresp. to Single- Stock Exploitation Boundaries Agreed TAC Official landings ICES landings 1987 Precautionary TAC Status quo (Shot) TAC Status quo (Shot) TAC No effort increase; TAC Status quo F; TAC TAC % of F(91)~2 800 t Reduce F < No increase in F No long-term gain in increasing F 1997 No advice No increase in effort Reduce F to F pa F < F pa < F < F pa < F < F pa < F < F pa < ) F < F pa 1) < ) F < F pa 1) < ) F < F pa 1) < ) F < F pa 1) < ) F < F pa 1) < ) F < F pa 1) < ) F < F pa 1) <3.19 Weights in 000 t. 1) Single-stock boundary and the exploitation of this stock should be conducted in the context of mixed fisheries. ICES Advice 2009, Book 6 113

118 Landings 6 Landings in 1000 t Fishing Mortality F(ages 3-8) F Flim Fpa Recruitment (age 1) Recruitment in millions Spawning Stock Biomass SSB in 1000 t SSB Bpa Shaded recruitment: GM Figure Sole in Division VIId (Eastern Channel). Landings, fishing mortality, recruitment, and SSB. 114 ICES Advice 2009, Book 6

119 Stock - Recruitment Recruitment (age 1) in millions SSB in 1000 t SSB-Rec. Bpa Yield and Spawning Stock Biomass per Recruit Yield (dashed line) Fishing Mortality (ages 3-8) SSB (line) SSB in 1000 t Precautionary Approach Plot Period Fishing Mortality (ages 3-8) F-SSB 2008 Flim Fpa Bpa Figure Sole in Division VIId (Eastern Channel). Stock recruitment, Yield-per-recruit, and precautionary approach plot. ICES Advice 2009, Book 6 115

120 18 SSB ('000 tonnes) 0.70 Fishing mortality: Recruitment. Age: Millions Figure Sole in Division VIId (Eastern Channel). Historical performance of the assessments. Note: some assessments have been indicative of trends only. 116 ICES Advice 2009, Book 6

121 Table Sole in Division VIId (Eastern Channel). Nominal landings (tonnes) as officially reported to ICES and used by the Working Group. Total used TAC Year Belgium France UK(E+W) others reported Unallocated* by WG ** * Unallocated mainly due misreporting ** Preliminary ICES Advice 2009, Book 6 117

122 Table Sole in Division VIId (Eastern Channel), summary of the assessment. Year Recruitment SSB Landings Mean F Age 1 Ages 3-8 thousands tonnes tonnes * Average * Recruitment 2009: GM ICES Advice 2009, Book 6

123 Saithe in Subarea IV (North Sea), Division IIIa (Skagerrak), and Subarea VI (West of Scotland and Rockall) State of the stock Spawning biomass in relation to precautionary limits Full reproductive capacity Fishing mortality in relation to precautionary limits Harvested sustainably Fishing mortality in relation to high longterm yield Appropriate Fishing mortality in relation to agreed target Appropriate Comment Based on the most recent estimates of SSB (in 2009) and fishing mortality (in 2008), ICES classifies the stock as having full reproductive capacity and being harvested sustainably. SSB is estimated to have been above B pa since From 2001 onwards, F has been at or below the target fishing mortality of 0.3. Management objectives The agreed EU Norway management plan (Annex ) includes: 1) Maintain the SSB above t, and 2) exploitation at F = 0.3 when the stock is above B pa. The management plan was evaluated by ICES in 2008 (ICES Advice 2008, Book 6, Section ), and the management plan is considered by ICES to be consistent with the precautionary approach in the short term (< 5 years). Reference points Precautionary approach Type Value Technical basis B lim t B loss = t (estimated in 1998). B pa t affords a high probability of maintaining SSB above B lim. F lim 0.6 F loss the fishing mortality estimated to lead to stock falling below B lim in the long term. F pa 0.4 implies that B eq > B pa and P(SSB MT < B pa ) < 10%. Targets F mgt 0.3 EU-Norway management plan (unchanged since 1998) Yield and spawning biomass per Recruit F-reference points (2009): Fish Mort Yield/R SSB/R Ages 3-6 Average last 3 years Fmax F Fmed HCR evaluation has shown that candidates for reference points consistent with high long-term yields and a low risk of depleting the productive potential of the stock are around F = 0.3. Single-stock exploitation boundaries Considering the options below, ICES advises on the basis of the agreed management plan that the landings should be no more than t in Exploitation boundaries in relation to existing management plans At the present SSB level, F should be no more than 0.3 to be in accordance with the management plan. This would give a 24% reduction in the TAC. However, there is a 15% TAC constraint when the stock is above B pa and applying this corresponds to landings of t in ICES Advice 2009, Book 6 119

124 Exploitation boundaries in relation to high long-term yield, low risk of depletion of production potential, and considering ecosystem effects The current fishing mortality ( average) is estimated at 0.29, which is close to the management plan target rate expected to lead to high long-term yields (F = 0.3). Exploitation boundaries in relation to precautionary limits An increase of F to 0.39 is possible while keeping SSB above B pa in This corresponds to landings of less than t in Short-term implications Outlook for 2010 Basis: F(2009) = F06 08 = ; R09 11 = GM88 06 = 122 ; SSB(2010) = 235 ; landings (2009) = 110. Rationale landings 2010 landings IIIa&IV ) landings VI ) Basis F 2010 SSB 2011 %SSB change 2) % TAC change 3) Zero catch F= Management 0.85*TAC plan (1.19*F sq ) Precautionary B pa approach (1.37*F sq ) Status quo *F sq *F sq *F sq F sq F MPtarget *F sq *F sq *F sq Weights in 000 t. 1) Landings split according to the average in , i.e. 90.6% in Subarea IV and Division IIIa and 9.4% in Subarea VI. 2) SSB 2011 relative to SSB ) Landings 2010 relative to TAC Management considerations The ICES advice applies to saithe in the three areas; Division IIIa, and Subareas IV and VI. Natural fluctuations in recruitment will result in a reduction of SSB to around B pa over the next few years. This is likely to lead to a decline in TAC advice. Following the management plan should provide an appropriate response. The reported landings have been lower than the TACs during the past seven years. Information from fishers indicates that this is due to very low prices for saithe combined with high fuel prices. However, there are also claims that the abundance of saithe has been reduced in the most recent years. By-catch of other demersal fish species occurs in some trawl fishery for saithe. Saithe is also taken as unintentional bycatch in other fisheries, and discards may occur if the vessels do not have a saithe quota. Impacts of fisheries on the ecosystems The effect on the bentic invertebrate community in the northern North Sea from all otter trawling is estimated to represent an annual mortality of approximately 25% of the standing-crop biomass.the MAFCONS and STECF dataset suggests that otter trawl effort directed at fish has declined since 1999 (Greenstreet et al., 2007). 120 ICES Advice 2009, Book 6

125 Factors affecting the fisheries and the stock Regulations and their effects In January 2002 the minimum mesh size (in bottom trawls for human consumption) was changed from 100 to 110 mm in EU waters and from 100 to 120 mm in Norwegian waters (the minimum mesh size for Norwegian vessels was set to 120 mm in both Norwegian and EU waters). In 2003 the mesh sizes were harmonized to 120 mm with the exception of the targeted saithe fishery (less than 3% cod bycatch), which remains at 110 mm. These variations might have contributed to changes in the exploitation pattern. Impacts of the environment on the fish stock A decrease in the mean weight-at-age has been observed in the past eleven years, but there is insufficient information to establish whether these reductions are linked to changes in the environment. The effects of a possible further decline in growth rates needs attention. There is no indication that the observed decline in weight-at-age is density dependent. Scientific basis Data and methods The stock is assessed using an age-based model (XSA), calibrated by two commercial cpue series and two survey indices. There are no discard estimates for the majority of this fishery. Discarding of saithe occurs in the non-targeted fisheries, but the level of discard is considered to be small compared to the total catch of saithe. Information from the fishing industry The reported landings in the last years have been lower than the TACs. Information from fishers indicates that very low prices on saithe, coupled with high fuel prices, are causing these reductions in targeted fisheries. Uncertainties in assessment and forecast The major uncertainty is the lack of information on year-class strength for ages 1 3. Therefore, IMR in Bergen, Norway began an acoustic survey along the western coast of Norway in 2006 to measure the relative abundance of saithe between 2 and 4 years old (when the saithe is distributed along the coast). However, the Norwegian acoustic survey will not be conducted in Another important problem with this assessment is the necessity to use commercial cpue for tuning as the survey series only contains usable information for ages 3-6. Since recruitment at age 3 tends to be poorly estimated in the XSA, the size of the 2005 year class is uncertain. Only very large relative errors will make a large impact on the forecast. Comparison with previous assessment and advice Compared to last years assessment, SSB in 2008 has been revised downwards by 14% and F in 2007 has been revised upwards by 6%. Recruitment in 2007 has been estimated 21% lower in this years assessment. The basis of the advice is unchanged. Sources of information Report of the Working Group on the Assessment of Demersal Stocks in the North Sea and Skagerrak, 6-12 May 2009 (ICES CM 2009/ACFM:10). Report of the Working Group on the Assessment of Demersal Stocks in the North Sea and Skagerrak, 6-12 May 2009 (ICES CM 2009/ACOM:10). ICES Norway and EC request on management plan for saithe in the North Sea and West of Scotland. ICES Advice, Book 6. Greenstreet, S. P. R., Robinson, L. A., Piet, G. J., Craeymeersch, J., Callaway, R., Reiss, H., Ehrich, S., et al The ecological disturbance caused by fishing in the North Sea. FRS Collaborative Report, 04/ pp. STECF Report of the First and Fourth meeting of the Subgroup on Review of Stocks (SGRST and SGRST-05-04) of STECF, Evaluation of the Cod recovery plan, Ispra, June and September ICES Advice 2009, Book 6 121

126 Saithe in IIIa and IV Year ICES Advice 2004 onwards: Single-Stock Exploitation Boundaries Predicted landings corresp. to advice Predicted landings correp. to single-stock exploitation boundaries Agreed TAC Official landings ICES landings 1987 Reduce F < % of F(86); TAC No increase in F; TAC No increase in F; TAC No increase in F; TAC No increase in F; TAC % of F(91) ~ t Reduce F by 30% No increase in F No increase in F No increase in F Reduce F by 20% Reduce F to F pa Reduce F by 30 % Reduce F by 20 % F < F pa < F < F pa < F < F pa < F according to man. plan * < F according to man. plan (< F pa ) * < F according to man. plan (< F pa ) * < F according to man. plan (< F pa ) * < F according to man. plan (< F pa ) * < F according to man. plan (< F pa ) * <107 Weights in 000 t. * Single-stock boundary and the exploitation of this stock should be conducted in the context of mixed fisheries. 122 ICES Advice 2009, Book 6

127 Saithe in VI Year ICES Advice 2004 onwards: Single-Stock Exploitation Boundaries* Predicted landings corresp. to advice Predicted catch corresp to single-stock exploitation boundaries Agreed TAC Official landings ICES landings 1987 F reduced towards F max % of F(86); TAC F < 0.3; TAC % of F(88); TAC Stop SSB decline; TAC Avoid further reduction in SSB < F = Lowest possible F Significant reduction in effort No increase in F Significant reduction in F % Reduction in F % reduction in F Reduce F by 30% Reduce F by 20% F < F pa < F < F pa < F < F pa <21 < F according to man. plan (< F pa ) <14 < F according to man. plan (< F pa )* * < F according to man. plan (< F pa ) * < F according to man. plan (< F pa ) * < F according to man. plan (< F pa ) * < F according to man. plan (< F pa ) * <11 Weights in 000 t. 1 Status quo catch. 2 Incomplete data. * Single-stock boundary and the exploitation of this stock should be conducted in the context of mixed fisheries. ICES Advice 2009, Book 6 123

128 Landings Landings in 1000 t F(ages 3-6) Fishing Mortality F Flim Fpa Recruitment (age 3) Recruitment in millions Spawning Stock Biomass SSB in 1000 t SSB Blim Bpa Figure Saithe in Subarea IV, Division IIIa (Skagerrak), and Subarea VI. Landings, fishing mortality, recruitment, and SSB. 124 ICES Advice 2009, Book 6

129 Stock - Recruitment 450 Recruitment (age 1) in millions SSB-Rec. Blim Bpa SSB in 1000 t Yield (dashed line) Yield and Spawning Stock Biomass per Recruit Fishing Mortality (ages 3-6) SSB (line) Precautionary Approach Plot Period SSB in 1000 t Fishing Mortality (ages 3-6) F-SSB 2008 Flim Fpa Blim Bpa Figure Saithe in Subareas IV and VI, and Division IIIa. Precautionary approach plot, yield-per-recruit analysis, and stock recruitment plot. ICES Advice 2009, Book 6 125

130 Figure Saithe (in Subareas IV and VI, and Division IIIa. Results of the North Sea Commission fishers survey Saithe in Subarea IV (North Sea) Division IIIa West (Skagerrak) and Subarea VI (West of Scotland and Rockall) SSB ('000 tonnes) Fishing mortality: Millions Recruitment. Age: Age: Figure Saithe in Subareas IV and VI, and Division IIIa. Historical performance of the assessments. Note: recruitment age was changed from 1 to 3 in ICES Advice 2009, Book 6

131 Table Saithe in Subarea IV, Division IIIa (Skaerrak), and Subarea VI. Landings in tonnes. Saithe IV and IIIa Country * 2005* * 2008* Belgium Denmark Faroe Islands France * Germany Greenland * * Ireland Netherlands * Norway Poland * Russia Sweden UK (E/W/NI) UK (Scotland) ** 9628** 11701** Total reported Unallocated W.G. Estimate TAC *Preliminary, 1 reportedbytacarea, IIa(EC), IIIa-d(EC) and IV, 2 Preliminary data reported in IVa **Scotland+E/W/NI combined Saithe VI Country * 2005* * Faroe Islands France * Germany Ireland Netherlands Norway Russia Spain UK (E/W/NI) UK (Scotland) ** 1419** Total reported Unallocated W.G.Estimate TAC *Preliminary, 1 reported by TAC area, IIa(EC), IIIa-d(EC) and IV **Scotland+E/W/NI combined SAITHE IV, IIIa and VI WG estimate TAC ICES Advice 2009, Book 6 127

132 Table Saithe in Subarea IV, Division IIIa (Skagerrak), and Subarea VI. Summary of stock assessment. Year Recruitment SSB Landings Mean F Age 3 Ages 3-6 thousands tonnes tonnes * Average *GM( ) 128 ICES Advice 2009, Book 6

133 Annex Management plan In 2008 EU and Norway renewed the existing agreement on a long-term plan for the saithe stock in the Skagerrak, the North Sea and west of Scotland, which is consistent with a precautionary approach and designed to provide for sustainable fisheries and high yields. The plan shall consist of the following elements. 1. Every effort shall be made to maintain a minimum level of Spawning Stock Biomass (SSB) greater than 106,000 tonnes (B lim ). 2. Where the SSB is estimated to be above 200,000 tonnes the Parties agreed to restrict their fishing on the basis of a TAC consistent with a fishing mortality rate of no more than 0.30 for appropriate age groups. 3. Where the SSB is estimated to be below 200,000 tonnes but above 106,000 tonnes, the TAC shall not exceed a level which, on the basis of a scientific evaluation by ICES, will result in a fishing mortality rate equal to *(200,000-SSB)/94, Where the SSB is estimated by the ICES to be below the minimum level of SSB of 106,000 tonnes the TAC shall be set at a level corresponding to a fishing mortality rate of no more than Where the rules in paragraphs 2 and 3 would lead to a TAC which deviates by more than 15 % from the TAC of the preceding year the Parties shall fix a TAC that is no more than 15 % greater or 15 % less than the TAC of the preceding year. 6. Notwithstanding paragraph 5 the Parties may where considered appropriate reduce the TAC by more than 15 % compared to the TAC of the preceding year. 7. A review of this arrangement shall take place no later than 31 December This arrangement enters into force on 1 January ICES Advice 2009, Book 6 129

134 Nephrops in Division IIIa (Skagerrak Kattegat) There are two Functional Units in Division IIIa: Skagerrak (FU 3) and Kattegat (FU 4). The advice for 2009 is biennial and valid for 2009 and 2010 (see ICES, 2008). The 2008 assessment had lead to the conclusion for the two FUs in Division IIIa that, given the apparent stability of the stocks, the current levels of exploitation appeared to be sustainable. The most recent assessment data compiled in 2009 do not indicate any changes in the state of the stock. Source of information ICES Report of the Working Group on the Assessment of Demersal Stocks in the North Sea and Skagerrak, 6 12 May 2009 (ICES CM 2009/ACOM:10) ICES, Report of the ICES Advisory Committee ICES Advice, Book 6. Table Nephrops in Division IIIa (Skagerrak Kattegat). Single-stock exploitation boundaries (advice), management and landings. Year ICES advice Recommended TAC Agreed TAC ICES landings ~ ~ Status quo TAC Status quo TAC Catches to be maintained at the 2000 level Catches to be maintained at the 2000 level Catches to be maintained at the 2000 level Catches to be maintained at the 2000 level No increase in effort No increase in effort No increase in effort Current effort appears to be sustainable Current effort appears to be sustainable Weights in 000 t. 1) Does not include discards. 130 ICES Advice 2009, Book 6

135 Nephrops in Subarea IV (North Sea) Nephrops are limited to a muddy habitat. This means that the distribution of suitable sediment defines the species distribution and the stocks are therefore assessed as eight separate functional units (Figure ): Section FU no. Name ICES area Statistical rectangles * 5 Botney Gut - Silver Pit IVb,c F1-F4; 35F2-F Farn Deeps IVb E8-E9; 37E Fladen Ground IVa E9-F1; 45-46E Firth of Forth IVb 40-41E7; 41E Moray Firth IVa E6-E7; 44E * 10 Noup IVa 47E * 32 Norwegian Deep lva F2-F6; 43F5-F * 33 Off Horn Reef lvb 39-41E4; 39-41E5 * The advice for these stocks was given in biannual advice in 2008, see ICES (2008a). Figure Nephrops Functional Units in the North Sea and Skagerrak/Kattegat region (see Section ). General features of Nephrops in IV. An overview of advice for different functional units is presented in Table Management considerations The overriding management consideration for these stocks is that management should be at the Functional Unit (FU) rather than the ICES Subarea level. Management at the Functional Unit level should provide the controls to ensure that catch opportunities and effort are compatible and in line with the scale of the resources in each of the stocks defined by the Functional Units. Current management of Nephrops in Subarea IV (both in terms of TACs and effort) does not provide adequate safeguards to ensure that local effort is sufficiently limited to avoid depletion of resources in Functional Units. In the current situation vessels are free to move between grounds, allowing effort to develop on some grounds in a largely uncontrolled way and this has historically resulted in inappropriate harvest rates from some parts. ICES Advice 2009, Book 6 131

136 This is a particular problem in the Farn Deeps where increased vessel activity from other parts of the UK occurred resulting in low stock levels. There are no precautionary reference points defined for Nephrops. This year ICES has provided advice on a range of catch options including a long term exploitation rate for Nephrops based on a number of considerations: For many stocks ICES considers that exploitation rates between F 0.1 and F max are an appropriate range of exploitation rates. For Nephrops both F 0.1 and F max are often well defined. There are a substantial number of studies on exploitation of fin fish indicating that F 0.1 is consistent with maximising sustainable long term yield, though this has not been studied directly for Nephrops and further work is required to ascertain whether fishing at F 0.1 is consistent with the management objective of maximising yield of Nephrops. F max is often considered too high an exploitation rate, leading to increasing risk to SSB without any substantial increases in yield. In addition for stocks with high discard rates a reduction of harvest rates often reduces the rates of exploitation of smaller individuals allowing larger numbers for the fishery in subsequent years. A limited number of management simulations have been carried out (Dobby, 2007) on two of the FU in the NS showing that harvest ratios of close to F 0.1 are appropriate for sustainable high long term yield with risks that ICES would consider precautionary. Ideally these simulations should be extended to other Nephrops FUs. The higher exploitation rates of the order of F max have not been explicitly tested but its unlikely that they will provided the same stability of yield and will have higher risks. These simulations did not explicitly deal with surveys that had different selection patterns from the fishery, there may be increases in risk associated with this, reinforcing the greater applicability of the lower exploitation rates. For a number of FUs in the North Sea (and Celtic Seas) the recent catches have been substantially higher than the rates implied by F 0.1. In the case of Firth of Forth (FU8) these catches have been even higher than the rate implied by F max but this coincided with an apparent increase in the stock in the last few years. In light of the above considerations, ICES advises that F should be in the range of F 0.1 to F max to maximize long term average yield without unduly risking SSB. ICES advice for individual functional units takes account of the current estimate of F and trend in SSB as follows: F relative to F 0.1 and F max SSB Stable or Increasing SSB Decreasing F > F max Reduce F to F max Reduce F to F 0.1 F max > F > F 0.1 Maintain current F Reduce F to F 0.1 F < F 0.1 Increase F to F 0.1 Maintain current F Where the new advice suggests a large change in landings, a constraint on the year to year change in catches as is typical of management plans and the Communication on Fishing Opportunities for 2010 [COM (2009) 224] might be considered. Some combinations of F and trend in SSB are included for completeness, even though not all of these combinations have been applied to North Sea Nephrops. In general, catches of cod in the Nephrops fisheries have been relatively low, particularly in recent years in inshore grounds of Subarea IV, but can vary amongst Functional Units. However, it is important that emerging year classes of cod should not be subject to high discard mortality. The capture of juvenile fish or other species such as haddock is also a problem in some of the Functional Units and discarding of these is a problem in some years. This problem is being addressed with the use of more selective gear and efforts are already being made in Scotland through the Conservation Credits scheme, requiring vessels targeting Nephrops to use gear with larger square meshed panels (110 mm). Subject to evaluation of the effectiveness of these measures, further action may be required to reduce discards. The advice is presented separately for each Functional Unit. In addition, there are increasing and significant landings from some isolated patches outside the Functional Units, most notably the Devil s Hole area. Table below shows that in 2008 overall landings in Subarea IV were around tonnes, similar to landings in Landings from other rectangles have risen steadily and amounted to over tonnes in To provide some guidance on appropriate future landings for these areas, the use of average landings of no more than 1500 tonnes ( ) could be considered (Table ). 132 ICES Advice 2009, Book 6

137 Impacts of fisheries on the ecosystem Trawling for Nephrops results in bycatch and discards of other species, including cod, haddock, and whiting. 80 mm is the predominant mesh size used in Nephrops fisheries and the resulting proportion of fish discarded can be high. Initiatives are in place to reduce discarding (see Regulations and their effects below). The high mud content and soft nature of Nephrops grounds means that trawling readily marks the seabed, trawl marks remaining visible for some time. Burrowing fauna can be seen re-emerging from freshly trawled grounds, implying that there is some resilience to trawling. Cod has been identified as a major predator of Nephrops in some areas. The generally low level of the cod in the North Sea is likely to have resulted in reduced predation. Multi-species models applied in the past to the exploitation of Irish Sea stocks indicated that management strategies which lead to an increase in the cod stock are associated with a reduction in Nephrops abundance. Therefore it may be expected that Nephrops stocks in the North Sea may decrease when cod recovers. Factors affecting the fisheries and the stock Regulations and their effects The implementation of the buyers and sellers regulations in the UK in 2006 considerably tightened up the levels of reporting for Nephrops, and the landings figures since then are considered to be more reliable. Recent increases in landings and lpue may result from the increase in reporting levels and do not necessarily reflect changes to the stock. A ban on the use of multi-trawl gears (3 or more trawls) for all Scottish boats was introduced from April 2008, limiting the expansion of effective effort. Days-at-sea regulations and recently introduced effort allocation schemes (kw*day) have reduced opportunities for directed whitefish fishing. STECF 2008 stated that the overall effort (kw*days) by demersal trawls, seines and beam trawls shows a substantial reduction since However, there have also been substantial changes in the usage of the different mesh size categories by the demersal trawls. In particular there has been a sharp reduction in usage of gears with a mesh size of between 100mm and 119mm (targeting whitefish), and a subsequent general increase in effort by vessels using smaller mesh sizes (targeting Nephrops for instance) or larger (targeting whitefish). The development of a Conservation Credits scheme in Scotland (the major contributor to landings from the Fladen Ground) requires all trawlers to implement more selective gears, including the use of 110 mm square mesh panels in 80 mm gear. This measure aims to reduce catches (and discards) of small fish, including whiting, haddock, and juvenile cod. Scientific basis Data and methods Assessments of the Nephrops Functional Units of Subarea IV utilized a number of approaches, including Underwater UWTV surveys (UWTV) surveys, length composition information, and basic fishery data such as landings and effort. Owing to uncertainties in the accuracy of historic landings and to inaccurate effort figures in some fisheries, increasing attention is paid to survey information and size composition data as an indicator of stock status. For those stocks without UWTV surveys, assessment is made on the basis of analysis of length compositions, trends in mean length for recruit classes and commercial CPUE. Biennial advice for these stocks was given in 2008 so no new advice is given this year. There have been important developments in the methodology to assess the status of Nephrops stocks. The use of UWTV surveys has enabled the development of fishery-independent indicators of abundance. STECF (2005) had suggested that a combination of an absolute abundance estimate from an UWTV survey and a harvest rate based on F 0.1 from a combined sex length cohort analysis (LCA) and the mean weight and selection pattern from the commercial fishery could be used to calculate appropriate landings. The approach has been further developed and evaluated by ICES workshops in 2007 and 2009 (ICES, 2007, ICES 2009b). The 2009 workshop addressed concerns raised regarding factors which could potentially bias the UWTV survey results. Major sources of bias were quantified for each survey and an overall bias correction factor derived which, when applied to the estimates of abundance from the UWTV survey allows them to be treated as absolute abundance levels. ICES Advice 2009, Book 6 133

138 In particular the workshop concluded that the UWTV surveys detect the burrows of Nephrops considerably smaller than the sizes of those taken by the fishery. Therefore the abundance estimates used to calculate the Harvest Ratios presented in the 2009 advice include a component of the stock that is too small to be exploited by the fishery. This has resulted in calculated Harvest Ratios appearing to have decreased in the current advice compared to previous estimates of Harvest Ratios. In essence, this is a scaling issue, not a change in exploitation rate. The previous proportion corresponding to fishing at F 0.1 were in the range of 15-20% whereas the revised values from the benchmark in 2009 are in the range of 8-10%. Information from the fishing industry Trends according to the North Sea fishers survey indicate disparate patterns of stock development. Long term increases in stock have been observed over most areas, but since 2007 the majority of areas show a small decline, except for Farn Deep (FU6) that shows a sharp decline (Figure ). Uncertainties in assessment and forecast For moderate exploitation rates the UWTV assessment provides an adequate basis for predicting catches. ICES groups WKNephTV (ICES 2007), WKNephBid (ICES 2008b), SGNepS (ICES 2009a) have progressively worked to reduce uncertainty and increase precision in the interpretation of survey data. There is a gap of at least 12 months (more commonly 18 months) between the survey and the start of the TAC year. It is assumed that the stock is stable during this period (i.e. recruitment and growth balance mortality). The effect of this assumption on realised harvest rates has not been investigated. The UWTV survey does not cover the complete spatial distribution of the stock, covering 4 out of 8 Functional Units and not the area outside the Functional Units. The area covered by the UWTV survey accounts for 79% of the landings in Landings from outside the FUs account for 8% of total landings. Vessel Monitoring System (VMS) data for vessels > 15 meters are being successfully used to match survey and fishery areas. The calculations of harvest ratio and F 0.1 are all based on yield-per-recruit analyses from length cohort analyses. These analyses utilise average length frequency data taken over a 3 year period and therefore apply to stocks in equilibrium. However, it is unlikely that the Nephrops stocks to which the approach has been applied are actually in equilibrium due to variable recruitment. F 0.1 estimates may vary in time due to changes in selection pattern. Prior to the implementation of Buyers and Sellers legislation in 2006 reporting rates are considered to have been low and hence the estimated Harvest Ratios prior to 2006 are also likely to have been underestimated. The reliability of fishery statistics is improving but the transition period is accompanied in some cases by large changes in landings which produce significant changes in the lpue and cpue series that cannot be completely attributed to changes in stock. Until a sufficient time series of reliable data has built up, use of fishery catch and effort data in the assessment process should be avoided. Comparison with previous assessment and advice For those stocks without UWTV surveys, advice given in 2008 was biennial and therefore no new advice is given this year. The advice basis for stocks with UWTV surveys has fundamentally changed since In 2008, ICES considered the UWTV indices to show relative trends and not absolute abundance. Consequently the advice was given in terms of maintaining landings at or below recent levels.. Sources of information ICES Workshop on the Use of UWTV Surveys for Determining Abundance in Nephrops Stocks throughout European Waters. WKNEPHTV. ICES CM 2007/ACFM:14. ICES, 2008a. Report of the ICES Advisory Committee ICES Advice, Book 6, 326pp. ICES 2008b. Workshop and training course on Nephrops burrow identification (WKNEPHBID). ICES CM 2008/LRC:03 ICES 2009a. Study Group on Nephrops Surveys (SGNEPS) ICES CM 2009/LRC:15 ICES 2009b. ICES Report of the Benchmark Workshop on Nephrops (WKNEPH), 2 6 March 2009, Aberdeen, UK. ICES CM 2009/ACOM:33. (awaiting publication). ICES 2009.c Report of the Working Group on the Assessment of Demersal Stocks in the North Sea and Skagerrak, 6 12 May 2009 (ICES CM 2009/ACOM:10). 134 ICES Advice 2009, Book 6

139 Dobby, H., Bailey, N., and Campbell, N The use of underwater TV surveys in the provision of advice for Nephrops stocks around Scotland. ICES CM 2007/O:23. Dobby, H Deriving appropriate harvest rates for the Nephrops stocks around Scotland. Working Document for ICES, 2007 WKNEPHTV. Laurenson, C. H North Sea Stock Survey NAFC Marine Centre, Shetland, UK. STECF Commission Staff Working Paper. 21 st Report of the Scientific, Technical and Economic Committee for Fisheries (Second Plenary Meeting). Brussels, 7 11 November STECF PLEN EUR EN, ISBN , ISSN , DOI /3484, 2008 Table Nephrops in Subarea IV. Summary of the advice by Functional Unit plus Other rectangles. Year Moray Firth (FU9) Noup (FU10) Fladen Ground (FU7) Norwegian Deeps (FU32) Farn Deeps (FU6) Firth of Forth (FU8) Botney Gut- Silver Pit (FU5) Off Horn s Reef (FU33) Other rectangles 2) Total advice 5) Agreed TAC 1) ICES landings Mgt Area MA F MA G MA S MA I MA H 1992 ~2.4 ~2.7 ~ < NA NA <10.9 NA NA NA ) NA <10.9 NA NA NA 9.5 6) NA < 1.8 < 0.24 < < 3.0 < < 1.4 NA <1.37 < < <1.2 < < 1.5 NA Weights in 000 t. 1) EU zone of Division IIa and Subarea IV. 2) Prior to advice for 2009, landings for other rectangles were included in 'Management Areas (MA). 3) No increase in effort. 4) Biennial advice given in ) It is not advised to manage these stocks as a single unit. 6) refers to advice for FU 5, 32 and 33 ICES Advice 2009, Book 6 135

140 * Tonnes Other IV FU 33 FU 32 FU 10 FU 9 FU 8 FU 7 FU 6 FU 5 Year Figure Nephrops in Subarea IV. Total landings divided into Functional Units and Other rectangles (tonnes). 136 ICES Advice 2009, Book 6

141 Figure Nephrops in Subarea IV. Results of the North Sea Commission fishers survey ICES Advice 2009, Book 6 137

142 Table Nephrops in Subarea IV. Officially reported landings (tonnes) by Functional Unit plus Other rectangles. Year FU 5 FU 6 FU 7 FU 8 FU 9 FU 10 FU 32 FU 33 Other IV Total * * Preliminary 138 ICES Advice 2009, Book 6

143 Nephrops in Botney Gut Silver Pit (FU 5) The advice for 2009 is biannual and valid for 2009 and 2010 (see ICES, 2008). Table Nephrops in Botney Gut Silver Pit (FU 5). Single-stock exploitation boundaries (advice), management, and landings. Year ICES advice Recommended landings ICES Landings ) No increase in effort No new advice, same as for No increase in effort No new advice, same as for Weights in 000 t. 1) Does not include discards. 2) Includes Off Horns Reef FU 33. ICES Advice 2009, Book 6 139

144 Nephrops in Farn Deeps (FU 6) State of the stock The UWTV survey, fishery data and length frequency data all point to the stock at the start of the 2008 fishing season continuing to be at a low level. Recruitment signals for Nephrops in 2008 appear to indicate low recruitment. Reference points F Harvest Technical basis reference point ratio F % WKNEPH 2009 F max 13.3% WKNEPH 2009 (unchanged since 2009) Single-stock exploitation boundaries ICES advises on the basis of exploitation boundaries in relation to high long term yield and low risk of depletion of production potential that the Harvest Rate for Nephrops fisheries should not exceed F This corresponds to landings of no more than t for the Farn Deeps stock. Basis: Bias corrected survey index (2008) = 965 Landings Rationale Harvest ratio 2010 (tonnes) 2% 318 4% 637 6% 955 F % % 1274 F % % % 1910 F max 13% % % % % 3184 Management considerations To protect the stock in this Functional Unit, management is required to be implemented at the Functional Unit level. Increases in abundance in other FUs (i.e. Firth of Forth and the Fladen grounds) are likely to translate to increases in TAC, increasing the risk of higher effort being deployed in this FU. The high cost of fuel combined with the relative coastal proximity of this ground may result in it attracting additional fishing effort which would be inadvisable given the current low level of the stock. Fishing effort in 2008 declined considerably due to fewer vessels visiting from Scotland and Northern Ireland. This brought the Harvest Rate in 2008 down to below the level considered to be equivalent to fishing at F 0.1. Without suitable controls on the movement of effort between Functional Units there is nothing to prevent the effort in 2010 returning to levels observed prior to 2008 all of which have been above the F 0.1 level and some of which have been considerably above the level of F max. Changes in fishing technology and fishing patterns Increases in the numbers of vessels using twin-rig gears observed in this area are likely to have increased the effective fishing power per kw hour. 140 ICES Advice 2009, Book 6

145 Poor catch rates during the and seasons resulted in several Scottish and Northern Irish vessels leaving the fishery early. Scientific basis Data and methods The UWTV survey has been conducted since Potential bias in survey design has been detected and accounted for in the assessment this year (see Data and methods section at the start of section ). Length composition data from catch and discard sampling programmes have been used from 2002 to estimate the length composition of landings. Data prior to 2002 were raised using landings sampling due to insufficient discard sampling in this period. Information from the fishing industry The North Sea Stock Survey by the fishing industry showed a long term increase in abundance since 2001 followed by a marked decrease in abundance in This is consistent with the assessment. Fishing industry opinions appear divided regarding incoming recruitment with some respondents considering it to be good and some poor. Uncertainties in assessment and forecast General comments are found at the start of section Direct landings sampling is likely to have missed portions of the landings landed as tails (as opposed to whole), leading to a significant overestimate of discarding above MLS. Comparison with previous assessment and advice The perception of the state of the stock has not changed since the assessment in The indicators show that the stock has been substantially reduced from a relatively high abundance in The advice in 2008 was based on recent landings as the UWTV surveys were considered inappropriate to use as absolute indices of abundance. Following the outcome of the benchmark in 2009, the major concerns of the UWTV survey have been addressed and the survey is now considered a reliable estimate of absolute abundance. The landings forecast for has changed considerably; in 2008 (for landings in 2009) it was less than 3000 t whereas the current advice for 2010 is for less than 1210 t based on F ICES Advice 2009, Book 6 141

146 Table Nephrops Farn Deeps (FU 6). Single-stock exploitation boundaries (advice), management, and landings. Year ICES advice Recommended landings Farn Deeps (FU6) Recommended landings FU6+FU8 ICES Landings FU6 1) ~ No increase in effort No increase in effort, harvest rate <15% No new advice, same as for No increase in effort and landings (2007) < 3.0 NA 2) 2010 Harvest Rate no greater than that equivalent to fishing at F 2008 Weights in 000 t. 1) Does not include discards. 2) Advice given at FU level only. <1.2 NA 2) 142 ICES Advice 2009, Book 6

147 Figure Nephrops Farn Deeps (FU 6): Long-term trends in landings, effort, lpues, and mean sizes of Nephrops. Abundance (millions) Year Figure Nephrops Farn Deeps (FU 6). Time-series of the bias adjusted UWTV survey index estimates, with 95% confidence intervals. ICES Advice 2009, Book 6 143

148 Figure Nephrops Farn Deeps (FU 6). Length composition of catch (dotted) and landed (solid) of males (right) and females left from 1996 (bottom) to 2007 (top). Mean sizes of catch and landings (using same line types ) is shown in relation to Minimum Landing Size (MLS). 144 ICES Advice 2009, Book 6

149 Table Nephrops Farn Deeps (FU 6). Official landings (tonnes). Year UK England UK Scotland Sub total Other countries** Total * * provisional na = not available ** Other countries includes Ne, Be and Dk Table Nephrops Farn Deeps (FU 6). Survey indices with and without bias adjustment Year Bias. adjusted Unadjusted Abundance Abundance (millions) ± 95% CI (millions) ± 95% CI NA NA NA NA 2000 NA NA NA NA ICES Advice 2009, Book 6 145

150 Nephrops Fladen Ground (FU 7) State of the stock UWTV observations indicate that the stock is fluctuating without obvious trend with estimates for the last 2 years increasing to the highest abundance in the series. Considering the UWTV result alongside the indications of stable or slightly increasing mean sizes in the length compositions of catches (of individuals >35mm carapace length) suggests that the stock is being exploited sustainably. The decline in mean length of smaller individuals in the catch may be indicative of recent good recruitment. Reference points F Harvest Technical basis reference point ratio F % WKNEPH 2009 F max 15.8% WKNEPH 2009 (unchanged since 2009) Single-stock exploitation boundaries ICES advises on the basis of exploitation boundaries in relation to high long term yield and low risk of depletion of production potential that the Harvest Rate for Nephrops fisheries should not exceed F 0.1. This corresponds to landings of no more than t for the Fladen Ground Basis: Bias corrected survey index (2008) = 7302 Rationale Harvest rate Landings 2010 (tonnes) 5.0% 8827 F % F % % % F max 15.8% % Management considerations To protect the stock in this Functional Unit, management is required to be implemented at the Functional Unit level. Nephrops fisheries in this area have a bycatch of cod. In 2005, high abundance of 0 group cod was recorded in Scottish surveys near to this ground. This year class of cod has subsequently contributed to slightly improved cod stock biomass and efforts are being made to avoid the capture of cod so that the stock can build further. In 2008 over 90% of the Scottish industry was operating under a voluntary Conservation Credits scheme and has implemented real time closures with a view to reducing unwanted bycatch of cod. Factors affecting the fisheries and the stock In the Fladen area the Nephrops stock is restricted to a generally continuous area of muddy sediments extending from N to 60 N, and from 1 W to 1 30 E, with other smaller patches to the north. The Fladen Ground is the largest known Nephrops ground where fishing activity can shift spatially so that effort can vary on parts of the ground. Nearly three quarters of the landings are made by single-rig vessels and one-quarter by twin-rig vessels. 80 mm mesh is the commonest mesh size. Nearly 40% of the Nephrops landings at Fladen are reported as bycatch, in fisheries which may be described as mixed. The effects of regulations The minimum landing size for Nephrops on the Fladen Ground is 25 mm carapace length. Discarding takes place at sea, and rates averaged over the period 2005 to 2007 for this stock were 18% by number, or 11% by weight. 146 ICES Advice 2009, Book 6

151 Changes in fishing technology and fishing patterns In the early years of the fishery, effort was primarily directed to a region that could be reached within 12 hours steaming from ports along the NE coast of Scotland. In recent years, logbook information and GPS loggers show that vessels are fishing more widely over the ground, including to the far eastern and northern edges of the extensive mud area. High fuel prices may limit steaming to some of these areas in Scientific basis Data and methods The UWTV survey has been conducted since Potential bias in survey design has been detected and accounted for in the assessment this year (see Data and methods section at the start of section ) Information from the fishing industry The NSCFP stock survey shows an increase in Nephrops between 2001 and 2002, a slight decrease to 2003, and a marked increase up to Stock levels are considered to be similar or slightly less in 2008 (Figure ). This information is broadly consistent with trends in the UWTV survey results. Uncertainties in assessment and forecast General comments are found at the start of section The UWTV survey is conducted over the main part of the ground, representing an area of around km 2 of suitable mud substrate (the largest ground in Europe). The Fladen Ground Functional Unit contains several patches of mud to the north of the ground which are fished, bringing the overall area of substrate to km 2. This area is not surveyed but would add to the abundance estimate. The absolute abundance estimate for this ground is therefore likely to be underestimated by the current methodology. Comparison with previous assessment and advice The perception of stock in 2008 is similar to that in 2007 from the assessment in The advice in 2008 was based on recent landings as the UWTV surveys were considered inappropriate to use as absolute indices of abundance. Following the outcome of the benchmark in 2009, the major concerns of the UWTV survey have been addressed and the survey is now considered a reliable estimate of absolute abundance. The landings forecast for 2010 (equivalent to fishing at F 0.1 ) is 16,419 tonnes. This is an increase of almost 4,000 tonnes on the reported landings in ICES Advice 2009, Book 6 147

152 Table Nephrops, Fladen (FU 7). Single-stock exploitation boundaries (advice), management, and landings. Year ICES advice Recommended Landings Fladen grounds (FU7) ICES Landings FU7 1) ~ < No increase of effort No increase in effort and harvest rate below 7.5% < No new advice, same as for 2007 < No increase in effort and recent average landings < Harvest Rate no greater than that equivalent to fishing at F 0.1 Weights in 000 t. 1) Does not include discards. < ICES Advice 2009, Book 6

153 Landings - International Denmark - All gears UK Scotland - All gears UK Scotland - Nephrops traw lers International Figure Nephrops, Fladen (FU 7). Long-term trends in landings, effort, lpues, and mean sizes of Nephrops Landings (tonnes) Effort ('000 hours trawling) Effort - Scottish and Danish Nephrops trawlers Scottish Danish Effort (days) LPUE - Scottish and Danish Nephrops trawlers Mean sizes - Scottish Nephrops trawlers LPUE (kg/hour trawling) Scottish Danish LPUE (kg/day) Mean size (mm carapace length) Catch Mal < 35 mm CL 36 Catch Fem < Landings Mal < 35 Landings Fem < Landings Mal > 35 Landings Fem > Abundance (millions) Year Figure Nephrops, Fladen (FU 7). Time-series of the bias adjusted UWTV survey index estimates, with 95% confidence intervals. ICES Advice 2009, Book 6 149

154 Table Nephrops, Fladen (FU 7). Total landings (tonnes). Year All Nephrops gears combined Single rig Multirig Landings Effort LPUE Landings Effort LPUE Landings Effort LPUE na na na na na na na na na na na na na na na na na na na na na na na na na na na na na na ICES Advice 2009, Book 6

155 Table Nephrops, Fladen (FU 7). Survey indices with and without bias adjustment. Values after 2002 have been adjusted for revised camera parameters Year Mean density Abundance 95% confidence interval Adjusted for bias 95% confidence interval burrows/m² millions millions millions millions ICES Advice 2009, Book 6 151

156 Nephrops in Firth of Forth (FU 8) State of the stock The evidence from the UWTV survey suggests that the population has been at a relatively high level since The UWTV survey information, taken together with information showing stable mean sizes, suggest that the stock is being exploited sustainably. Reference points F Harvest Technical basis reference point ratio F % WKNEPH 2009 F max 13.7% WKNEPH 2009 (unchanged since 2009) Single-stock exploitation boundaries ICES advises on the basis of exploitation boundaries in relation to high long term yield and low risk of depletion of production potential that the Harvest Rate for Nephrops fisheries should not exceed F max. This corresponds to landings of no more than tonnes for the Firth of Forth stock. Basis: Bias corrected survey index (2008) = 881 Rationale Harvest rate Landings 2010 (tonnes) 5.0% 572 F % % % 1715 F max 13.7% % 2287 F % 2802 Management considerations To protect the stock in this Functional Unit, management is required to be implemented at the Functional Unit level. The advised landings for 2010 imply a reduction of 37% relative to the 2008 landings (2 500 t). ICES advice is for F max instead of F 0.1 because increased landings in earlier years have coincided with an increase in stock implying perhaps that the present level of exploitation could be sustainable. Even though in the longer term the differences in total catch are expected to be small, the move to F 0.1 as a target would imply significant initial reductions in catch. In this case a stepwise approach could be considered. A reduction of the catch corresponding to F max could be an intermediate step toward F 0.1 (as a proxy for F msy ). Alternatively, a constraint on the year to year change in catches as is typical of management plans and the Communication on Fishing Opportunities for 2010 [COM (2009) 224] might be considered. Nephrops discard rates in this Functional Unit are high and there is a need to reduce these and to improve the exploitation pattern. An additional reason for suggesting improved selectivity in this area relates to bycatch. It is important that efforts are made to ensure that other fish are not taken as unwanted bycatch in this fishery which uses 80mm mesh. Larger square mesh panels implemented as part of the Scottish Conservation Credits scheme should help to improve the exploitation pattern for some species such as haddock and whiting. Factors affecting the fisheries and the stock Landings from the Firth of Forth fishery are predominantly reported from Scotland, with very small contributions from England. The area is periodically visited by vessels from other parts of the UK. There is a risk that owing to fuel costs vessels which would normally fish further offshore will locate to inshore grounds. The Firth of Forth is close inshore and is of small geographic size so that significant influx of effort will have deleterious effects. Catches of marketable bycatch fish are small from this area and there are few other species in the area for vessels to target. 152 ICES Advice 2009, Book 6

157 Estimated discarding rates are 31% by number in the Firth of Forth in This arises from the use of mainly smallmeshed (80 mm) nets and the population size structure which appears to arise from slower growth. Local markets for small whole Nephrops are seasonally important. Changes in fishing technology and fishing patterns The Firth of Forth resident fleet contains numerous small boats which are generally restricted to more sheltered inshore waters. There are, however, observations of shifts of Nephrops fishing by larger vessels from the fleet to grounds such as the Devil s Hole ( an offshore ground not included as part of a Functional Unit). Scientific basis Data and methods The UWTV survey has been conducted annually since 1993 (no surveys in 1995 and 1997). Monthly market sampling and quarterly on-board observer sampling provides good coverage of length compositions. Potential bias in survey design has been detected and accounted for in the assessment this year (see Data and methods section at the start of section ) Information from the fishing industry The NSCFP survey (Figure ) does not include specific information for the Firth of Forth. Uncertainties in assessment and forecast General comments are found at the start of section Comparison with previous assessment and advice The perception of the stock in 2008 is very similar to that of the stock in 2007 The advice in 2008 was based on recent landings as the UWTV surveys were considered inappropriate to use as absolute indices of abundance. Following the outcome of the benchmark in 2009, the major concerns of the UWTV survey have been addressed and the survey is now considered a reliable estimate of absolute abundance.. The landings forecast for 2010 (<1 567 t) is considerably lower than for 2009 (<2500t). This is due to using F max as the target F for this stock in the current advice. ICES Advice 2009, Book 6 153

158 Table Nephrops, Firth of Forth (FU 8). Single-stock exploitation boundaries (advice), management, and landings. Year ICES advice Recommended landings Firth of Forth (FU8) Recommended landings FU6+FU ~ No increase in effort No increase in effort, harvest rate <15% No new advice, same as for No increase in effort and recent average landings < ICES Landings FU8 1) 2010 Harvest Rate no greater than that equivalent to fishing at F max Weights in 000 t. 1) Does not include discards. 2) It is not advised to manage these stocks as a single unit. < ) 154 ICES Advice 2009, Book 6

159 Landings (tonnes) Landings - International UK Scotland - All gears 3000 UK Scotland - Nephrops traw lers International Effort ('000 hours trawling) Effort - Scottish Nephrops trawlers LPUE - Scottish Nephrops trawlers Mean sizes - Scottish Nephrops trawlers LPUE (kg/hour trawling) Mean size (mm carapace length) Catch Mal < 35 mm CL Catch Fem < 35 Landings Mal < 35 Landings Fem < Landings Mal > 35 Landings Fem > Figure Nephrops, Firth of Forth (FU 8). Long-term trends in landings, effort, lpues, and mean sizes of Nephrops Abundance (millions) Figure Year Nephrops, Firth of Forth (FU 8). Time-series of bias adjusted UWTV survey abundance estimates (in millions), with 95% confidence intervals, ICES Advice 2009, Book 6 155

160 Figure Nephrops, Firth of Forth (FU 8). Catch length frequency distribution and mean sizes (red line). 156 ICES Advice 2009, Book 6

161 Table Nephrops, Firth of Forth (FU 8). Total landings (tonnes). Year All Nephrops gears combined Single rig Multirig Landings Effort LPUE Landings Effort LPUE Landings Effort LPUE na na na na na na na na na na na na na na na na na na na na na na na na na na na na na na ICES Advice 2009, Book 6 157

162 Table Nephrops, Firth of Forth (FU 8). Survey indices with and without bias adjustment. Values after 2002 have been adjusted for revised camera parameters Year Mean density Abundance 95% confidence interval Adjusted for bias 95% confidence interval burrows/m² millions millions millions millions ICES Advice 2009, Book 6

163 Nephrops in Moray Firth (FU 9) State of the stock The evidence from the UWTV survey suggests that the population is stable, but at a lower level than that evident from The UWTV survey information, taken together with information showing stable mean sizes, suggest that the stock is being exploited sustainably. Reference points F Harvest Technical basis reference point ratio F % WKNEPH 2009 F max 16.6% WKNEPH 2009 (unchanged since 2009) Single-stock exploitation boundaries ICES advises on the basis of exploitation boundaries in relation to high long term yield and low risk of depletion of production potential that the Harvest Rate for Nephrops fisheries should not exceed F This corresponds to landings of no more than tonnes for the Moray Firth stock. Basis: Bias corrected survey index (2008) = 478 Rationale Landings Harvest 2010 rate (tonnes) 5.0% 520 F % % 1040 F % % 1560 F max 16.6% % 2080 Management considerations To protect the stock in this Functional Unit, management is required to be implemented at the Functional Unit level. A reduction of the catch corresponding to F 2008 can be considered as an intermediate step toward F 0.1 (as a proxy for F msy ). Alternatively, a constraint on the year to year change in TAC as is typical of management plans and the Communication on Fishing Opportunities for 2010 [COM (2009) 224] might be considered. There is a bycatch of other species in the Moray Firth area. It is important that efforts are made to ensure that unwanted bycatch is kept to a minimum in this fishery. Current efforts to reduce discards and unwanted bycatches of cod under the Scottish Conservation credits scheme, include the implementation of larger meshed square mesh panels and real time closures to avoid cod. Factors affecting the fisheries and the stock In the Moray Firth area the Nephrops stock inhabits a single continuous area of muddy sediment extending from north of Fraserburgh to Inverness. The Moray Firth Nephrops ground is located close to the Scottish coast and is exploited almost exclusively by UK vessels. Landings from this fishery are predominantly reported from Scotland, with very small contributions from England in the mid-1990s, but none recently. Regulations and their effects Discarding rates averaged over the period 2006 to 2008 for this stock were about 6% by number. This represents a marked reduction in discarding rate compared to the average for the period 2003 to This may arise from the increasing use of larger size meshes in the northern North Sea, although reduction in recruitment may also account for this change. ICES Advice 2009, Book 6 159

164 Scientific basis Data and methods UWTV survey estimates are available for and from 1996 onwards. Length compositions from the commercial fishery are available from Potential bias in survey design has been detected and accounted for in the assessment this year (see Data and methods section at the start of section ) Uncertainties in assessment and forecast General comments are found at the start of section Information from the fishing industry The NSCFP survey (Figure ) does not include specific information for the Moray Firth. Comparison with previous assessment and advice The perception of the stock in 2008 is similar to that of the stock in 2007 The advice in 2008 was based on recent landings as the UWTV surveys were considered inappropriate to use as absolute indices of abundance. Following the outcome of the benchmark in 2009, the major concerns of the UWTV survey have been addressed and the survey is now considered a reliable estimate of absolute abundance. The landings forecast for 2010 (< t) is considerably lower than for 2009 (< 1 800t). This is due to using the status quo F (F 2008 ) as the target F for this stock in the current advice. Table Nephrops, Moray Firth (FU 9). Single-stock exploitation boundaries (advice), management, and landings. Year ICES advice Recommended landings Moray Firth (FU9) Recommended landings FU9+FU10 ICES landings FU9 1) ~ Status quo TAC Status quo TAC Catches to be maintained at the 2000 level Catches to be maintained at the 2000 level Catches to be maintained at the 2000 level Catches to be maintained at the 2000 level No increase in effort No increase in effort, and harvest rate below 15% 2008 No new advice, same as for No increase in effort and recent average landings < Harvest Rate no greater than that equivalent to fishing at F 2008 < ) Weights in 000 t. 1) Does not include discards. 2) It is not advised to manage these stocks as a single unit. 160 ICES Advice 2009, Book 6

165 Landings (tonnes) Landings - International UK Scotland - All gears 3000 International Effort ('000 hours trawling) Effort - Scottish Nephrops trawlers LPUE - Scottish Nephrops trawlers Mean sizes - Scottish Nephrops trawlers LPUE (kg/hour trawling) Mean size (mm carapace length) Catch Mal < 35 mm CL 34 Catch Fem < Landings Mal < 35 Landings Fem < Landings Mal > 35 Landings Fem > Figure Nephrops, Moray Firth (FU 9). Long-term trends in landings, effort, lpues, and mean sizes of Nephrops Abundance (millions) Figure Year Nephrops, Moray Firth (FU 9). Time-series of bias adjusted UWTV survey abundance estimates (in millions), with 95% confidence intervals, ICES Advice 2009, Book 6 161

166 Figure Nephrops, Moray Firth (FU 9), Catch length frequency distribution and mean sizes (red line). 162 ICES Advice 2009, Book 6

167 Table Nephrops, Moray Firth (FU 9). Nominal landings as officially reported (tonnes). Year All Nephrops gears combined Single rig Multirig Landings Effort LPUE Landings Effort LPUE Landings Effort LPUE na na na na na na na na na na na na na na na na na na na na na na na na na na na na na na ICES Advice 2009, Book 6 163

168 Table Nephrops, Moray Firth (FU 9). Survey indices with and without bias adjustment. Values after 2002 have been adjusted for revised camera parameters Year Mean density Abundance 95% confidence interval Adjusted for bias 95% confidence interval burrows/m² millions millions millions millions ICES Advice 2009, Book 6

169 Nephrops in Noup (FU 10) The advice for 2009 is biannual and valid for 2009 and 2010 (see ICES, 2008). Table Nephrops, Noup (FU 10). Single-stock exploitation boundaries (advice), management, and landings. Year ICES advice Recommended landings Noup (FU10) Recommended landings FU9+FU10 ICES Landings FU10 1) ~ Status quo TAC Status quo TAC Catches to be maintained at the 2000 level Catches to be maintained at the 2000 level Catches to be maintained at the 2000 level Catches to be maintained at the 2000 level No increase in effort No increase in effort, and recent average landings No new advice, same as for ) No increase in effort, and average landings 2003 < No new advice, same as for 2009 < ) Weights in 000 t. 1) Does not include discards. 2) Based on a 15% harvest rate applied to UWTV survey abundance data. Includes Moray Firth (FU 9). 3) It is not advised to manage these stocks as a single unit. ICES Advice 2009, Book 6 165

170 Nephrops in Norwegian Deeps (FU 32) The advice for 2009 is biannual and valid for 2009 and 2010 (see ICES, 2008). Table Nephrops in the Norwegian Deep (FU 32). Single-stock exploitation boundaries (advice), management, and landings. Year ICES advice Recommended Landings FU32 TAC Agreed 1 ICES Landings FU32 2) 1987 < < < No TAC agreed No TAC agreed No increase in effort No increase in effort No new advice, same as for No increase in effort No new advice, same as for Weights in 000 t. Norwegian zone of Subarea IV. 1) TAC for EU vessels only. 2) Does not include discards. 166 ICES Advice 2009, Book 6

171 Nephrops off Horn s Reef (FU 33) The advice for 2009 is biannual and valid for 2009 and 2010 (see ICES, 2008). Table Nephrops, FU 33 (Off Horn Reef). Single-stock exploitation boundaries (advice), management, and landings. Year ICES advice Recommended Landings FU33 ICES Landings FU33 1) < ) No increase in effort No new advice, same as for No increase in effort No new advice, same as for Weights in 000 t. 1) Does not include discards. 2) Includes Farn Deeps (FU6). ICES Advice 2009, Book 6 167

172 Herring in Division IIIa and Subdivisions (Western Baltic spring spawners) State of the stock Spawning biomass in relation to precautionary limits Fishing mortality in relation to precautionary limits Fishing mortality in relation to high longterm yield Undefined Undefined Overfished NA Fishing mortality in relation to agreed target Comment In the absence of agreed reference points, the state of the stock cannot be evaluated. SSB has been stable in recent years but is expected to decline rapidly due to poor recruitment. Fishing mortality has been stable and is estimated at 0.37, well above the candidate for F msy. From 2004 onwards, recruitment has been declining and is now at a record-low. Management objectives There are no explicit management objectives for this stock. Reference points There are no precautionary approach reference points agreed for this stock. Yield and spawning biomass per Recruit F-reference points (2009): Fish Mort Yield/R SSB/R Ages 3-6 Average last 3 years Fmax* F Fmed *Fmax is not well defined. Candidates for reference points consistent with high long-term yields and a low risk of depleting the productive potential of the stock are around F 0.1. Preliminary HCR evaluations are consistent with this view and have shown that candidates for F msy can be found in the region of F = 0.25 (see section ). Single-stock exploitation boundaries ICES advises on the basis of exploitation boundaries in relation to long-term yield that fishing at the candidate Fmsy fishing mortality (0.25) implies catches in 2010 not larger than t in the entire distribution area. 168 ICES Advice 2009, Book 6

173 ICES Advice 2009, Book Short-term implications Outlook for 2010 Basis (for Western Baltic spring spawning herring WBSS): F(2009) = 0.29 [Catch constraint]; R =GM( )=2225 million; SSB(2009) = 142; catch (2009) = 45 a). Catches are for herring in Division IIIa and Subdivisions 22 24, see further in Section on North Sea Autumn Spawning herring (NSAS). Catch options and results for WBSS herring only: Catch options for WBSS and NSAS herring: Division IIIa, Subdivisions and Division IVaE Division IIIa and Subdivisions ) 1) III a IVaE SSB SSB % SSB IIIa % TAC Catch F Fleet F Fleet C Fleet D Fleet A change Catch Fleet F Fleet C Fleet D change Rationale 2010 Basis ) 3) 3) 4) ) Zero catch 0 F = % % High longterm yield 39.8 F sq * % % Status quo 45.4 F sq * % % 48.7 F sq * % % 57.3 F sq * % % 65.9 F sq * % % Weights in 000 t a) assuming a utilisation of the TAC/bycatch ceiling of 97% (F-fleet), 52% (D-fleet) and 65% (C-fleet). 1) Ratio of herring catches between different fleets and areas in 2009 is based on the 2009 TACs (or bycatch ceiling in case of fleet D), ratio between the different herring stocks in IIIa is based on the 2008 catch ratios. The later ratio cannot be predicted and may therefore deviate significantly from the assumed ratio... 2) As in 2008 a catch of 0.1 t of WBSS herring taken in the Eastern North Sea is assumed. 3) For spring spawning stocks, the SSB is determined at spawning time and is influenced by fisheries between 1 st January and spawning time. 4) SSB (2011) relative to SSB (2010). 5) Catches (2010) relative to TAC 2009 (SD IIIa + IIIa bycatch ceiling = = 73.3 kt). To derive the total herring catch for Division IIIa (right hand side of the table), predicted catches of NSAS (as advised in section ) have to be added to the advised maximum catches of WBSS in the area. The total catch by fleet is only compatible with the advice for WBSS if the values given for NSAS are treated as maximum catches. Thus the resulting catch options were also used as constraints for catch options for the NSAS herring (Section ). Note that the right hand side of the table is for illustrative purposes only and is not part of the ICES advice; the ratio of TACs between areas is not fixed and there are several options for TACs compatible with the removal of WBSS advised by ICES. Explanation on fleet coding: Area Fleet Description North Sea A Directed herring fisheries with purse-seiners and trawlers. Bycatches in industrial fisheries by Norway are included. B Bycatches of herring taken under EU regulations. Division IIIa C Directed herring fisheries with purse-seiners and trawlers. D Bycatches of herring caught in the small-mesh fisheries. Sub-Divisions F All herring fisheries in Subdivisions ICES Advice 2009, Book 6 169

174 Catch options for mixed stocks in Division IIIa based on short-term predictions for Western Baltic Spring- Spawning herring (WBSS) Catch options for the whole stock of Western Baltic Spring-Spawning herring (WBSS) can be partitioned into catches by area. Catches of WBSS herring in Division IIIa also imply catches of North Sea Autumn-Spawning (NSAS) herring which constitute part of the total catch in that area. ICES catch predictions versus management TAC ICES advises on catch options by fleet for the entire distribution of the two herring stocks separately, whereas herring is managed by areas cross-sectioning the geographical distribution of the stocks (see the following text diagram). The catch options for 2010 are based on the TAC proportions by fleet and area in 2009 and, for IIIa, on the observed stock composition (WBSS vs. NSAS) in catches taken in Short-term predictions are based on an expected catch in 2009 of t of Western Baltic spring spawning stock taking into account the TACs by fleet for 2009, potential misreporting and the assumed proportion of Western Baltic spring spawning herring in the catches in Division IIIa. To make fleet wise catch options for the prediction year it is assumed that the TAC distribution by fleet in 2010 will be equal to It is also assumed that there will be allowed a subtraction of 20% of the Norwegian quota that is transferred to the A-fleet (as NSAS). Further it is assumed that each fleet catches its total TAC. Finally it is assumed that the 2008 proportions of WBSS by fleet hold for The proportions of WBSS in catches were 0.71 in the C- fleet, 0.37 in the D-fleet and 1.00 in the F-fleet and further a constant catch of 120 t of WBSS caught in the A-fleet in Division IVa East. Management considerations North Sea Autumn-Spawning and the Western Baltic Spring-Spawning herring stocks are exploited and managed simultaneously in Division IIIa. Hence, the management of the herring fisheries in Division IIIa influences both stocks. Recruitment of Western Baltic herring has been reduced by 15-35% annually from 2004 onwards. The estimated strength of the 2008 year class is the lowest of the whole times series, and amounts to only a quarter of the average. There is no indication that recruitment would return to the previous level in the near future. The poor year classes have not yet fully contributed to the SSB but will increasingly do so in the near future. In this situation, there is no alternative to reduce F significantly to avoid a drastic decline of the SSB. ICES has used the mean recruitment from (year classes) for the short-term prediction which might be overly optimistic in the present situation. Factors affecting the fisheries and the stock Regulations and their effects Corrections for misreporting by area have been incorporated in the assessment. In recent years, ICES has calculated that a substantial part of the catch reported as taken in Division IIIa by fleet C was actually taken in Subarea IV. These catches have been allocated to the North Sea stock and accounted for under the A fleet. Regulations allowing quota transfers from Division IIIa to the North Sea were introduced as an incentive to decrease misreporting for the Norwegian part of the fishery. Recent Working Group estimates of 30% misreporting in Division IIIa may be underestimating the problem because not all countries supply this information to ICES. The quota for the C fleet and the bycatch quota for the D fleet (see above) are set for the NSAS and the WBSS stocks together. The implication for the catch of NSAS must also be taken into account when setting quotas for the fleets that exploit these stocks. 170 ICES Advice 2009, Book 6

175 Changes in fishing technology and fishing patterns There have been only minor changes in the fishery technology in recent years. Impact of the environment on the fish stock Herring in Division IIIa and Subdivisions are migratory. There are feeding migrations from the Western Baltic into more saline waters of Division IIIa and the eastern parts of Division IVa. There are indications from parasite infections that yet unknown proportions of sub-stocks spawning at the southern coast in the Baltic proper may perform similar migrations. Western Baltic herring recruitment has been reduced by 15-35% annually from 2004 onwards and is now at a record low. North Sea herring, with which Western Baltic herring shares the same environment at least for part of the year, has also produced only very small year classes since In a recent recruitment analysis for different Baltic herring stocks, the Baltic Sea Index (BSI) reflecting Sea Surface Temperature (SST) was the main predictor for Western Baltic herring (Cardinale et al., in press). There are no indications of systematic changes in growth or age at maturity, and candidate key stages for reduced recruitment are probably the egg or the larval stage. The specific reasons for reduced egg or larval survival are not known. Further investigation of the causes of the poor recruitment will require targeted research projects. Scientific basis Data and methods The otolith microstructure method has been used to calculate the proportion of spring and autumn spawners caught in these areas for all catch and survey data in the period An analytical FLICA assessment is based on catch data and the results of two acoustic and one larval survey. Information from the fishing industry VMS data confirm that area misreporting from the North Sea to the Skagerrak has declined in proportion with the reduction in reported landings. Identified misreported catch has been moved to the appropriate areas and are thus taken into account in the assessment. Uncertainties in assessment and forecast There is no firm basis to predict the fraction of NSAS in the catches by the C- and D-fleets. The proportions of the two stocks as well as the distribution pattern of the fishery in the Eastern North Sea and in Division IIIa changes dynamically year by year. This is probably influenced by the year class strength of the two stocks and their relative geographical distributions, as well as by fleet behavior reacting to herring availability and management decisions. The strength of a year class is not firmly estimated before the year class has been followed for 2 3 years. However, the introduction of a larval 0-group recruitment index (N20) in 2008 appears to contribute valuable and consistent information to the estimate of the 1-winter ringers in the assessment. Comparison with previous assessment and advice A benchmark assessment was carried out in The update assessment this year shows a reduction of 23% of the estimated fishing mortality in 2007 and a 21% increase for the SSB in However trends in recruitment and SSB are similar. In 2008 ICES advised an immediate reduction in F to candidate for Fmsy = In the light of the continuing reduction of recruitment, the basis for the advice did not change. Source of information Report of the Herring Assessment Working Group for the Area South of 62 N, March 2009 (ICES CM 2009/ACFM:03). Cardinale, M., Mölmann, C., Bartolino, V., Casini, M., Kornilovs, G., Raid, T., Margonski, P.,Raitaniemi, L., and Gröhsler, T. (in press). Climate and parental effects on the recruitment of Baltic herring (Clupea harengus membras) populations. Conditionally accepted by MEPS. ICES Advice 2009, Book 6 171

176 Table Herring in Division IIIa and Subdivisions (Western Baltic spring spawners). Single stock exploitation boundaries (advice), management and catches. Year ICES Advice Pred. catch corresp. to advice Agreed TAC IIIa 2 ICES catch of Stock 22 IIIa IV Total Reduction in F No increase in F TAC TAC TAC TAC Increased yield from reduction in F; reduction in juvenile catches TAC If required, TAC not exceeding recent catches If required, TAC not exceeding recent catches IIIa: managed together with autumn spawners 22 24: if required, TAC not exceeding recent catches 1998 Should be managed in accordance with North Sea autumn spawners 1999 IIIa: managed together with autumn spawners 22 24: if required, TAC not exceeding recent catches 2000 IIIa: managed together with autumn spawners 22 24: if required, TAC not exceeding recent catches 2001 IIIa: managed together with autumn spawners 22 24: if required, TAC not exceeding recent catches 2002 IIIa: managed together with autumn spawners 22 24: if required, TAC not exceeding recent catches ~60 for Subdivs ~50 for Subdivs ~50 for Subdivs Reduce F < Separate management regime for this stock <92 Reduce F 2005 Separate management regime for this stock Status quo F 2006 Separate management regime for this stock /47.5* Status quo F 2007 Separate management regime for this stock /49.5* Status quo F Separate management regime for this stock /45* Reduce F by 20% towards F Separate management regime for this stock < /27.2* Reduce F to F = Separate management regime for this stock Reduce F to F = 0.25 <39.8 Weights in 000 t. 1 Catch in Subdivisions Including mixed clupeoid TAC and bycatch ceiling in small-mesh fishery. 3 Human consumption in Division IIIa, not incuding industrial bycatch or mixed clupeoids, but including North Sea Autumn Spawner catch in fleet C. * separate TAC for SD ICES Advice 2009, Book 6

177 Landings 250 Landings in 1000 t F(ages 3-6) Fishing Mortality Recruitment in billions Recruitment (age 0) Spawning Stock Biomass SSB in 1000 t Figure Herring in Subdivisions and Division IIIa (spring spawners). Landings, fishing mortality, recruitment, and SSB. Estimates are shown in grey recruitment taken as GM ICES Advice 2009, Book 6 173

178 Stock - Recruitment Recruitment (age 0) in billions SSB in 1000 t Yield and Spawning Stock Biomass per Recruit Yield (dashed line) SSB (line) Fishing Mortality (ages 3-6) SSB in 1000 t Precautionary Approach Plot Period Fishing Mortality (ages 3-6) F-SSB 2008 Figure Herring in Subdivisions and Division IIIa (spring spawners). Stock recruitment, yield and SSB per recruit, precautionary approach. ICES Advice 2009, Book 6

179 Figure Herring in Subdivisions and Division IIIa (spring spawners). Historical performance of the assessment. The last data point for SSB is a prediction, for Recruitment the last data points is GM ICES Advice 2009, Book 6 175

180 Table Herring in Subdivisions and Division IIIa (spring and autumn spawners). Landings ( 000 t). Year Skagerrak Denmark Faroe Islands Germany Norway Sweden Total Kattegat Denmark Sweden Total Sub. Div Denmark Germany Poland Sweden Total Sub. Div. 23 Denmark Sweden Total Grand Total Year 1998 (2) 1999 (2) (5) 2002 (4) (1,3) (1) Skagerrak Denmark Faroe Islands Germany Norway Sweden Total Kattegat Denmark Sweden Total Sub. Div Denmark Germany (6) Poland Sweden Total Sub. Div. 23 Denmark Sweden Total Grand Total (1) (2) (3) (4) (5) (6) Preliminary data. Revised data for 1998 and 1999 Bold= German revised data for tonnes of Danish landings are missing, see text section The Danish national management regime for herring and sprat fishery in Subdivision 22 was changed in 2002 The total landings in Skagerrak have been updated for due to Norwegian misreportings into Skagerrak. This value is incorrect but could not be corrected in subsequent calculations before the completion of the meeting. The correct value is ICES Advice 2009, Book 6

181 Table Herring in Subdivisions and Division IIIa (spring spawners). Summary of the assessment. Year Recruitment SSB Landings Mean F Age 0 at spawning time Ages 3-6 thousands tonnes tonnes * Average * Recruitment is GM ( ). SSB is predicted. ICES Advice 2009, Book 6 177

182 Herring in Subarea IV and Divisions IIIa and VIId (North Sea autumn spawners) State of the stock Spawning biomass in relation to precautionary limits Increased risk Fishing mortality in relation to precautionary limits Harvested sustainably Fishing mortality in relation to high longterm yield Overfished Fishing mortality in relation to agreed target Above target Comment Based on the most recent estimates of SSB and fishing mortality, ICES classifies the stock as being at risk of having reduced reproductive capacity and harvested sustainably. The SSB in autumn 2008 was estimated at 1.0 million t, and is expected to remain below B pa (1.3 million t) in F 2-6 in 2008 was estimated at 0.24, above the management target F 2-6 (for this state of the stock = 0.14). The year classes since 2002 are estimated to be among the weakest since the late 1970s. Management objectives In November 2008 EU-Norway have agreed on an adjusted management plan (see annex) taking account of recent poor recruitment. ICES has evaluated this management plan (WKHMP ICES CM 2008 ACOM:27) and concluded that the plan is consistent with the precautionary approach. Reference points Type Value Technical basis B lim t < 0.8 million t; poor recruitment has been experienced B Precautionary pa 1.3 million t B trigger in the previous harvest control rule approach F lim not defined F pa F 0-1 = 0.12 F 2-6 = 0.25 Target Fs in the previous harvest control rule Targets F mt F 0-1 = 0.05 F 2-6 = 0.25 If SSB >1.5 million tonnes, B trigger (based on simulations) F 0-1 = 0.05 F 2-6 = 0.25 (0.15*( SSB)/700000) If SSB between 0.8 and 1.5 million tonnes (based on simulations) F 0-1 = 0.04 F 2-6 = 0.10 If SSB <0.8 million t (based on simulations) Precautionary reference points unchanged since 1999, target reference points since Yield and spawning biomass per Recruit F-reference points (2009): Fishing Yield/R SSB/R Mort Ages 2-6 average last 3 years F max F F 35%SPR HCR evaluation has shown than candidates for reference points which are consistent with high long-term yields and a low risk of depleting the productive potential of the stock are around the target values in the management plan. Single-stock exploitation boundaries ICES advises on the basis of the agreed EU Norway management plan. Following the agreed management plan implies catches of t for fleet A and t for fleet B in 2010 in the North Sea. Short-term implications Catch forecasts are presented below for different scenarios of sharing the catch amongst fleets, producing the total fishing mortality given in the table headings. The forecasts are based on an assumption of the fisheries in 2009, taking 178 ICES Advice 2009, Book 6

183 the TAC with an overshoot by the A-fleet of 13% corresponding to the overshoot seen in the last three years, and bycatches following the agreed management plan. The seven scenarios presented below are based on an interpretation of the harvest control rule or other options and show the range of options for differing overall exploitation rates. The distribution of catches among the fleets is only illustrative, and other options with similar overall exploitation rates are possible: a) No fishing; b) Catches that are estimated lead to SSB>Bpa in 2011; c) A 15% decrease in A fleet in TAC between 2009 and 2010; d) The EU-Norway management plan with larger catches of approximately 40% for the C and D fleet e) The EU Norway management plan; f) A roll over TAC from 2009 to 2010 of 171 kt for the A fleet; g) A 15% increase in A fleet in TAC between 2009 and 2010; Since the current management plan only stipulates overall fishing mortalities for juveniles and adults, making fleet-wise predictions for four fleets that are more or less independent provides different options for The consequence of other combinations of catch options can be explored on request. Outlook assuming a TAC constraint for fleet A in 2009 Basis: Intermediate year (2009) with catch constraint R 09 (ICA)=32832 million; R =GM(YC )=21465 million F fleet A F fleet B F fleet C F fleet D F 0-1 F 2-6 Catch fleet A Catch fleet B Catch Fleet C Catch fleet D SSB Scenarios for prediction year (2010) F Fleet A F-VALUES BY FLEET AND TOTAL CATCHES BY FLEET RESULTS F fleet B F fleet C F fleet D F 0-1 F 2-6 Catch fleet A Catch fleet B Catch fleet C Catch fleet D SSB SSB ) 2011 %SSB change 2) %TAC change fleet A 3) a % -100% b % -36% c % -15% d % -5% e % -4% f % 0% g % +15% Weights in 000 t. Shaded areas are considered not in accordance with the precautionary approach. All numbers apply to North Sea autumn-spawning herring only. 1) For autumn spawning stocks, the SSB is determined at spawning time and is influenced by fisheries between 1 st January and spawning. 2) SSB 2011 relative to SSB ) Calculated landings 2010 relative to TAC Fleet definitions: Fleet A: Directed herring fisheries with purse-seiners and trawlers (32 mm minimum mesh size) in the North Sea. Bycatches in the Norwegian industrial fisheries are included. Fleet B: Herring taken as bycatch in the small-mesh fisheries in the North Sea under EU regulations (mesh size less than 32 mm). Fleet C: Directed herring fisheries in Skagerrak and Kattegat with purse-seiners and trawlers (32 mm minimum mesh size). Fleet D: Bycatches of herring caught in the small-mesh fisheries (mesh size less than 32 mm) in Skagerrak and Kattegat. ICES Advice 2009, Book 6 179

184 Management considerations A reduction in fishing mortality to close to the target fishing mortality is expected to be achieved in 2009 (Figure ). The SSB is expected to increase slightly both in 2010 and further in 2011, indicating that the current management has the potential to reverse the decline in the stock and stabilize it above the present level. The 2008 year class is estimated to be within the range of recent low recruitments. ICES assumes that the recruitment will remain at the low level. Delay in implementing substantial reductions in catch by not following the management plan has resulted in the SSB being at greater risk of being below B lim and lower catches (Figure ). Landings of herring taken in the North Sea but reported from other areas such as Divisions IIa and IIIa and from Division VIaN have increased in 2008 compared to The total amount of catch in excess of the TAC in the human consumption fishery has increased as a proportion of the TAC to 17% ( t). Management of the autumn-spawning herring must be considered together with the Western Baltic Spring-Spawning herring. The options selected for the C- and D-fleets are compatible with the advised exploitation of Western Baltic Spring Spawners assuming a catch for 2010 of tonnes (see Section 6.4.7) and are 7.4 and 3.7 thousand tonnes of North Sea autumn spawning herring for C and D fleets respectively. Downs herring The sub-tac for Divisions IVc and VIId was established for the conservation of the spawning aggregation of Downs herring. The Downs herring has returned to its pre-collapsed state and is now again a major component of the stock. It is probable that exploitation of Downs herring has been relatively high. In the absence of data to the contrary ICES proposes that a share of 11% of the total North Sea TAC (average share ) would still be appropriate for Downs herring. Management plan evaluations The new management plan has been evaluated and the plan is consistent with the precautionary approach. Impact of fisheries on the ecosystems Herring is considered to have a major impact on most other fish stocks as prey and predator and is itself prey for seabirds and sea mammals. Herring spawning and nursery areas, being near the coasts, are particularly sensitive and vulnerable to anthropogenic influences. The most serious of these is the increasing extraction of marine sand and gravel and the development of wind farms on existing and historic spawning beds. The human consumption fisheries for herring are considered relatively clean, with little bycatch of other fish and almost no disturbance to the seabed. The limited evidence from observer programmes suggest that discarding of herring is not wide-spread. Juvenile herring are bycaught in the industrial fisheries.. Factors affecting the fisheries and the stock Regulations and their effects In EU waters, slippage and high grading of herring is now prohibited in the North Sea herring fishery (EC Council Reg No 43/2009) as long as the fish are above minimum landing size and quota is available. The consequences of new regulation are unknown but to thought have little impact on the catch estimates. In the Norwegian purse seine fisheries, slipping is permitted under conditions where the fish is assumed to be viable (likely to survive). This rule is currently under revision. High grading and discarding is not permitted. Changes in fishing technology and fishing patterns. There have been no major changes to fishing technology and fishing patterns of the fleets that target North Sea herring. Impacts of the environment on the fish stock North Sea herring has recently produced six poor year classes in a row, which has never been observed before at this SSB. Indications suggest that the 2008 year class has is slightly higher but still lies within the bounds of the recent series of poor year classes. The survival of the larvae has been poor (Payne et al., 2009). The specific reasons for this are not known. The trends in herring recruitment are similar to the warming of the water on the spawning grounds and changes in the hydrography. These changes may be linked to the AMO (Atlantic Multidecadal Oscillation), and they are also associated with changes in the zooplankton community. Further investigation of the causes of the poor recruitment will require targeted research projects.scientific basis 180 ICES Advice 2009, Book 6

185 Data and methods The stock assessment and projections used data from the landings and from four survey time-series of North Sea herring. Each of these surveys targets a different life stage of the herring. The landings and catch-at-age data is collated from Subarea IV and Divisions VIId and IIIa. Some national catch estimates were corrected for unallocated and misreported catch. Denmark and Norway provided information on bycatches of herring in the industrial fishery. These are the main countries conducting these fisheries. Information from the fishing industry Representatives from the pelagic industry after the ICES expert group express concern that for the last 2-3 years the fishermen s observations of the abundance of juvenile herring in the Eastern, Central and Southern part of the North Sea were higher than anticipated given the results of the assessment. The working group has found underestimation of the 2007 year class and corrected for this in the current assessment, however, other year classes are still estimated at the same low level. Uncertainties in assessment and forecast ICES carried out a benchmark assessment of the North Sea autumn-spawning herring stock in 2006, checking the appropriate use of the survey indices and catch. The present assessment is an update of the bench mark assessment. Surveys show slightly divergent signals. The occurrence of misreported and unallocated catches leads to uncertainties in the assessment. The overall assessment gives a consistent basis for advice (Figure ). There is no evidence that discarding of herring is a major problem at present for the estimation of population dynamics or conservation of North Sea herring. Comparison with previous assessment and advice The assessment is consistent with the assessment of The new assessment has revised the size of the 2007 year class but it is still estimated as poor and comparable with the other recent year classes. The basis advice is different from last year. Last year ICES advised to implement a new management plan, this year it advises to follow the new management plan. Source of information Report of the Herring Assessment Working Group for the Area South of 62 N, March ICES CM 2009/ACOM:03). Report of the Workshop on Herring Management Plans (WKHMP). ICES CM 2008/ACOM:27. Payne MR, Hatfield EMC, Dickey-Collas, M, Falkenhaug, T, Gallego, A, Gröger, J., Licandro, P, Llope, M, Munk, P, Röckmann, C, Schmidt, JO & Nash, RDM (2009). Recruitment in a changing environment: the 2000s North Sea herring recruitment failure. ICES J Mar Sci. 66: ICES Advice 2009, Book 6 181

186 Table Herring caught in the North Sea (Subarea IV and Division VIId). Single stock exploitation boundaries (advice), management and catch/landings. Year ICES Advice Predicted catch corresp. to advice Agreed TAC 1 Bycatch ceiling Fleet B ICES Lndgs. 4 IV, VIId ICES Catch 5 IV, VIId ICES Catch Autumn spawners IIIa, IV, VIId 1987 TAC TAC TAC TAC TAC TAC No increase in yield at F > No increase in yield at F > Long-term gains expected at lower F % reduction of agreed TAC F = F(adult) = 0.2, F(juv)< F(adult) = 0.2, F(juv)< F(adult) = 0.2, F(juv)< F(adult) = 0.2, F(juv)< 0.1 See scenarios F(adult) = 0.2, F(juv)< 0.1 See scenarios F(adult) = 0.25, F(juv)=0.12 See scenarios F(adult) = 0.25, F(juv)=0.1 See scenarios F(adult) = 0.25, F(juv)=0.1 See scenarios F(adult) = 0.25, F(juv)=0.12 See scenarios Bring SSB above B pa by 2008 See scenarios F(adult) = 0.17, F(juv)=0.08 (MP) See scenarios Adopt one of the new proposed HCRs See scenarios F(adult) = 0.15, F(juv)=0.05 (MP) See scenarios Weights in 000 t. 1 Catch in directed fishery in IV and VIId. 2 Revision of advice given in Revised in June 1996, down from Landings are provided by the working group and do not in all cases correspond to official statistics. 5 ICES catch includes unallocated and misreported landings, discards, and slipping. 182 ICES Advice 2009, Book 6

187 Figure Herring in Subarea IV, Divisions VIId & IIIa (autumn spawners), stock summary. Fishing mortality is expressed as averages over ages 2 6 (dots) and 0 1 (line). B pa (B trigger in the previous Harvest control rule) and B lim, F pa 2-6 and F pa 0-1 are shown. Recruitment is expressed as one year olds (0 winter ring). ICES Advice 2009, Book 6 183