REPORT OF THE WORKING GROUP ON THE ASSESSMENT OF NORTHERN SHELF DEMERSAL STOCKS (WGNSDS)

Transcription

1 ICES WGNSDS REPORT 2006 ICES Advisory Committee on Fishery Management ACFM:13 REPORT OF THE WORKING GROUP ON THE ASSESSMENT OF NORTHERN SHELF DEMERSAL STOCKS (WGNSDS) MAY 2005 MURMANSK, RUSSIA

2 International Council for the Exploration of the Sea Conseil International pour l Exploration de la Mer H.C. Andersens Boulevard DK-1553 Copenhagen V Denmark Telephone (+45) Telefax (+45) info@ices.dk Recommended format for purposes of citation: ICES Report of the Working Group on Working Group on the Assessment of Northern Shelf Demersal Stocks (WGNSDS), May 2005, Murmansk, Russia. ACFM: pp. For permission to reproduce material from this publication, please apply to the General Secretary. The document is a report of an Expert Group under the auspices of the International Council for the Exploration of the Sea and does not necessarily represent the views of the Council International Council for the Exploration of the Sea

3 ICES WGNSDS report 2006 i Contents 1 GENERAL INTROCUCTION Participants Terms of reference Stock Assignments in Environmental and Ecosystem Information Environmental Drivers of Productivity Impacts of Fisheries on the Ecosystem Description of Fisheries Fisheries to the West of Scotland and Rockall Fisheries in the Irish Sea Fisheries in other areas covered by the WGNSDS Enumeration of Capacity and Effort Regulations TAC Regulations Other Regulations Recent ICES Advice in the Context of Mixed Fisheries Mixed fisheries advice for 2004: Mixed fisheries advice for 2005: Recommendations Acknowledgements DATA AND METHODS Catch Data Official Landings Misreported Landings Discards Biological Sampling Compilation and Aggregation of Catch Data Biological Parameters of Stocks Fleet Catch per Unit Effort Data Fishery-Independent Surveys Underwater TV surveys for Nephrops Information Provided as Working Documents WD1: Comparison of abundance indices for VIIa plaice WD2: Evaluation of the Irish Sea Cod Recovery Plan WD3: Sampling units & auxiliary variables in discards estimation WD4: Discarding by the Irish demersal fishery WD5: Biological parameters of Irish demersal stocks, WD6: Analysis of length-structured survey data WD7: ISCSBTS Abundance indices for VIIa plaice WD8: Historic discard levels of VIIa plaice WD9: Weights at age of VIIa plaice WD10: Stock structure of whiting in the Irish Sea... 41

4 ii ICES WGNSDS report WD11: Rockall haddock trawl acoustic survey WD12: Russian investigations of Rockall haddock, WD13: Hydrography west of the British Isles, WD14: Update of DARD VIIa plaice abundance indices WD15: FSP - Effect of mesh size on catches of VIIa plaice WD16: FSP - Surveys of VIIa gadoids WD17: SURBA 3.0: Technical Manual WD18: Shelf edge and deepwater fixed net fisheries Sequential Population Analysis and Recruit Estimation: Catch-at-Age Assessments Population Analysis and Recruit Estimation: Survey-Based Assessments Short-term Predictions and Sensitivity Analyses Reference Points Quality Control and Documentation of Procedures Software References Cod in sub-area VI Cod in Division VIa Stock definition and the fishery Catch data Commercial catch-effort series and research vessels surveys Age compositions and mean weights at age Natural mortality and maturity at age Data screening and exploratory runs Medium-term stock projections Yield and biomass per recruit Biological reference points Quality of the assessment Cod in Division VIb HADDOCK IN SUB-AREA VI Haddock in Division VIa The fishery Catch Data Commercial catch-effort data and research vessel surveys Age compositions and mean weights at age Natural mortality, maturity and stock weights at age Catch at age analysis Estimating recruiting year class abundance Long-term trends in biomass, fishing mortality and recruitment Short-term stock predictions Medium-term projections Yield and biomass per recruit Reference points Quality of assessment Management considerations Haddock in Division VIb The fishery Catch data

5 ICES WGNSDS report 2006 iii Commercial catch-effort data Research vessel surveys Age compositions and mean weights at age Natural mortality and maturity at age Catch at age analysis WHITING IN SUB-AREA VI Whiting in Division VIa Stock definition and the fishery Catch data Commercial catch-effort data and research vessel surveys Age composition and mean weights at age Natural mortality and maturity at age Data screening and exploratory runs Whiting in Division VIb ANGLERFISH (on the NORTHERN SHELF & IIa) Anglerfish in Sub-Area VI The fishery Catch data Commercial catch-effort data Research vessel surveys Length compositions Natural mortality and maturity Anglerfish in the North Sea & Skagerrak The fishery Catch data Commercial catch-effort data Research vessel surveys Length compositions Natural mortality and maturity Analysis of CPUE data Anglerfish on the Northern Shelf (combined IIIa, IV and VI) The fishery CPUE analysis Reference points for Management evaluation Quality of the assessment Management considerations Anglerfish in Division IIa The fishery Catch data Commercial catch-effort data Research vessel surveys Length and age compositions and mean weights at age Natural mortality and maturity Management considerations MEGRIM IN SUB-AREA VI Megrim in Division VIa ICES advice applicable to 2004 and Management applicable in 2004 and The fishery in

6 iv ICES WGNSDS report Stock Structure Catch Data Official Catch statistics Revisions to the catch data Commercial catch-effort data and research vessels survey Age compositions and mean weights at age Landings age & length compositions and mean weights at age Discard age compositions and mean weights at age Natural mortality, maturity and stock weight at age Catch-at-age analysis Data Screen Commercial Catch Data Comparison with last years assessment Reference points Quality of the assessment Landings and LPUE data Discards Surveys Management considerations Megrim in Division VIb The fishery in Official Catch statistics Quality of the catch data Management applicable to 2003 and Commercial catch-effort data and research vessels survey Catch age compositions and mean weights at age Management considerations COD IN Division VIIa The Fishery ICES advice applicable to 2004 and Management applicable in 2004 and The fishery in Commercial catch-effort data and research vessel surveys Landings, age composition and mean weights-at-age Natural mortality and maturity at age Survey and catch-at-age analyses Data screening and exploratory runs Estimating recruiting year class abundance Long-term trends in biomass, fishing mortality and recruitment Stock predictions Medium-term predictions Yield and biomass per recruit Reference points Quality of the assessment Management considerations Haddock in Division VIIa The fishery

7 ICES WGNSDS report 2006 v ICES advice applicable in 2004 and Management applicable in 2004 and The fishery in Catch data Official catch statistics Revision of Catch data Quality of Catch data Commercial catch-effort and research vessel surveys Age composition and mean weights at age Catch age composition and mean weights at age in the catch Discard age composition Natural mortality, maturity and stock weights at age Survey and Catch-at-age analysis Data screening and exploratory runs Estimating recruiting year class abundance Long term trends of biomass, recruitment and fishing mortality Short-term stock predictions Medium term predictions Yield and biomass per recruit Reference points Quality of the assessment Management considerations WHITING IN DIVISION VIIa The Fishery ICES advice applicable to 2004 and Management applicable in 2004 and The Fishery in Catch Data Official Catch Statistics Revisions to Catch Data Quality of the Catch data Commercial catch-effort and research vessel surveys Commercial catch and effort data Research vessel surveys Age compositions and mean weights at age Landings age composition and mean weights at age Discards age composition Natural mortality, maturity and stock weight at age Catch-at-age analysis Data Screening and Exploratory Runs Estimating recruiting year class abundance Long-term trends in biomass, fishing mortality and recruitment Short-term stock predictions Medium Term Projections Yield and Biomass per Recruit Reference Points Quality of the Assessment Management considerations

8 vi ICES WGNSDS report Plaice in Division VIIa The fishery ICES advice applicable to 2004 and Management applicable in 2004 and The fishery in Official catch statistics Revisions to catch data Quality of the catch data Commercial catch effort data and research vessel surveys Age compositions and mean weights at age Landings age composition and mean weights at age Natural mortality and maturity at age Catch-at-age analysis Data screening Final ICA run Comparison with last year's assessment Estimating recruiting year-class abundance Long-term trends in biomass, fishing mortality and recruitment Stock predictions Medium-term projections Yield and Biomass Per Recruit Reference points Quality of the assessment Commercial data Model formulation Survey data Biological information Management considerations Sole in Division VIIa The fishery ICES advice applicable to 2004 and Management applicable in 2004 and The fishery in Catch data Official Catch Statistics Revisions to Catch data Quality of the Catch data Commercial catch-effort and research vessel surveys Age compositions and mean weights at age Landings age composition and mean weight-at-age Discards age composition Natural mortality, maturity Catch-at-age analysis Data screening and exploratory runs

9 ICES WGNSDS report 2006 vii Estimating recruitment year class abundance Long-term trends in biomass, fishing mortality and recruitment Short-term catch predictions Medium-term predictions Yield and biomass per recruit Reference points Quality of the assessment Management considerations NEPHROPS IN Sub-Area VI Nephrops in Management Area C ICES advice applicable to 2004 and Management applicable in 2004 and North Minch The Fishery Catch data Commercial catch-effort data and research vessel surveys Age composition and mean weights-at-age Natural mortality, maturity at age and other biological parameters Catch-at-age-analyses South Minch The Fishery Catch data Commercial catch-effort data and research vessel surveys Age composition and mean weights-at-age Natural mortality, maturity at age and other biological parameters Catch-at-age-analyses Clyde The Fishery Catch data Commercial catch-effort data and research vessel surveys Age composition and mean weights-at-age Natural mortality, maturity at age and other biological parameters Catch-at-age-analyses Other Nephrops Stocks Stanton Bank Shelf edge west of Scotland Management Area C Management Considerations NEPHROPS IN DIVISION VIIa Nephrops in Management Area J The Fishery Irish Sea East (FU14) The fishery in Catch data Commercial catch-effort data and research vessel surveys Length at Age composition and mean weights-at-age Natural mortality and maturity at age Catch-at-age-analyses Irish Sea West (FU15) The Fishery

10 viii ICES WGNSDS report Catch data Commercial catch-effort data and research vessel surveys Length at Age composition and mean weights-at-age Natural mortality and maturity at age Catch-at-age-analyses Management Area J Management Considerations

11 ICES WGNSDS report GENERAL INTRODUCTION 1.1 Participants Mike Armstrong Nick Bailey Otte Bjelland Richard Briggs Helen Dobby Sergey Golovanov (Part-time) Steven Holmes Vladimir Khlivnoy Colm Lordan Sara-Jane Moore Sten Munch-Petersen Rick Officer (Chair) Pieter-Jan Schön Robert Scott Evgeny Sentyabov (Part-time) Ian Tuck Willy Vanhee Vladimir Vinnichenko United Kingdom (England and Wales) United Kingdom (Scotland) Norway United Kingdom (Northern Ireland) United Kingdom (Scotland) Russian Federation United Kingdom (Scotland) Russian Federation Ireland Ireland Denmark Ireland United Kingdom (Northern Ireland) United Kingdom (England and Wales) Russian Federation United Kingdom (Scotland) Belgium Russian Federation 1.2 Terms of reference 2ACFM10: The Working Group on the Assessment of Northern Shelf Demersal Stocks [WGNSDS] (Chair: R. Officer, Ireland) will meet at Murmansk, Russia from May 2005 to: a) assess the status of and provide management options for 2006 for the stocks of cod, haddock, whiting, anglerfish, and megrim in Subarea VI, for cod, haddock, whiting, plaice, sole in Division VIIa, and Nephrops Functional Units 11, 12, 13, 14, and 15, and for anglerfish stocks in Subarea IV and Divisions IIa, IIIa and VIa; b) for the stocks mentioned in a) perform the tasks described in C. Res. 2ACFM01. WGNSDS will report by 27 May 2005 for the attention of ACFM. Terms of Reference a) is considered within the individual stock sections which give the results of attempts to assess each stock. Term of Reference b) (C. Res. 2ACFM01) requires that several tasks be undertaken in 2005 for each of the stocks mentioned in Term of Reference a). These tasks are listed below, and henceforth referred to as Terms of Reference c) to j): c) for stocks where it is considered relevant, review limit reference points (and come forward with new ones where none exist) and develop proposals for management strategies including target reference points if management has not already agreed strategies or target reference points (or HCRs) following the guidelines from SGMAS (2005) and AMAWGC (2004 and 2005); d) comment on the outcome of existing management measures including technical measures, TACs, effort control and management plans;

12 2 ICES WGNSDS report 2006 e) based on input from WGRED incorporate (where appropriate) existing knowledge on important environmental drivers for stock productivity and management into assessment and prediction, and important impacts of fisheries on the ecosystem; f) update the description of fisheries exploiting the stocks, including major regulatory changes and their potential effects. The description of the fisheries should include an enumeration of the number, capacity and effort of vessels prosecuting the fishery by country; g) where misreporting is considered significant provide information on its distribution on fisheries and the methods used to obtain the information; h) provide for each stock information on discards (its distribution in time and space) and the method used to obtain it. Describe how it has been considered in the assessment; i) provide on a national basis an overview of the sampling of the basic assessment data for the stocks considered; j) provide specific information on possible deficiencies in the 2005 assessments including, at least, any major inadequacies in the data on landings, effort or discards; any major inadequacies in research vessel surveys data, and any major difficulties in model formulation; including inadequacies in available software. The consequences of these deficiencies for both the assessment of the status of the stocks and the projection should be clarified. Term of Reference c) is dealt with in the individual stock Chapters under the heading Reference Points. For VIIa cod, this Term of Reference is also considered in WD2: Evaluation of the Irish Sea Cod Recovery Plan. Terms of Reference d), e) and f) are dealt with in Sections 1.7, 1.4, and 1.5 respectively. Term of Reference g) is dealt with in the individual stock Chapters under the heading Quality of the Catch Data, and also under Section Term of Reference h) is dealt with in the individual stock Chapters under the heading Discards Age Composition, and also under Section Term of Reference i) is dealt with under Section Term of Reference j) is dealt with in the individual stock Chapters under the heading Quality of the Assessment.

13 ICES WGNSDS report Stock Assignments in 2005 ICES has established a system with different types of assessments (Observation, Benchmark, Update and Experimental) for stock assessment Working Groups. C.Res. 2ACFM01 outlined the following plan for WGNSDS stocks in 2005: Observation list Benchmark Update Experimental None Haddock VIb Whiting VIa Megrim VIb Cod VIa Anglerfish IV & VI Cod VIIa Megrim VIa Haddock VIIa Plaice VII Whiting VIIa Sole VII all Nephrops stocks WGNSDS notes that this list does not list the WG s recovery plan stocks (Cod VIa and VIIa) on the Observation list, does not properly define the assessment area for several stocks, does not include Haddock VIa, and, requests update assessments for stocks without accepted assessments. Following discussions of the proposed Stock Assignments between the WGNSDS and ACFM Chairs the WG proceeded on an alternative basis in The WGNSDS considers only one stock (Irish Sea sole) which is not on the observation list, and for which an update assessment exists. WGNSDS 2005 therefore intended to conduct an update assessment for VIIa sole using the Same Procedure As Last Year (SPALY). Most other stocks considered by the WGNSDS 2005 were treated as experimental assessments. The assessment types attempted at WGNSDS 2005 for each stock are introduced at the beginning of the individual stock Chapters. The stocks considered by WGNSDS are tabulated in Table 1.1, along with the type of assessment carried out, and an indication of whether the WGNSDS 2005 approach reflects a change to previous practice. 1.4 Environmental and Ecosystem Information Term of reference e) asks the WG to incorporate existing knowledge on important environmental drivers for stock productivity and management into assessment and predictions, based on input from WGRED 2005 (ICES 2005). The WG was further asked to consider important impacts of fisheries on the ecosystem noted by WGRED. For the Norwegian Sea WGRED noted a general warming climate during the last 20 years with the last three years as outstanding at about 1ºC above mean for period in a section running north-west off the coast at approximately N62. WGNSDS considered that this might have contributed to the northward expansion of the fishery for anglerfish but no corroborating data were available to substantiate this inference. WGRED also noted large stocks of all major pelagic stocks. WGNSDS considered that this could affect the growth of anglerfish in the area positively, as the growing stock of spring spawning herring spends much of the year (wintering and spawning) in areas where anglerfish is distributed along the coast. For the North Sea WGRED noted warming, increased primary production, but that the seasonality of phytoplankton blooms are less distinct.

14 4 ICES WGNSDS report 2006 For the areas of most interest to WGNSDS (defined in the WGRED report as the Celtic Seas ) WGRED noted that there has been a overall warming in areas to the west of Scotland and Ireland, similar changes have been documented to have had substantial effects on distribution (and therefore catchability) and productivity of demersal and some pelagic stocks in other areas, but the effects on stocks in the Celtic Seas are not known. WGRED therefore suggested that extra care should be taken in the examination of all tuning indices, because of the possible effects on q, and any effects on stock productivity due to the very warm waters would affect the success of recovery plans for stocks in these seas. Whilst WGRED did not make the same observation for the North Sea, WGNSDS considers that similar concerns about the effects of warming on catchability would apply to the North Sea, and may have influenced the CPUE series presented for anglerfish. At WGNSDS 2005 the heavy reliance on survey data for most assessments required a very thorough examination of tuning series, and particularly any trends in their catchability. WGNSDS notes that no experts attended the WGRED meeting with particular experience of the Northern Shelf. WGNSDS therefore included information not available to WGRED which may contribute to an improved understanding of environmental drivers of productivity on the Northern Shelf Environmental Drivers of Productivity Hydrographic observations for much of the area of the Northern Shelf are presented in WD13: Hydrography west of the British Isles, Of particular note are the changes in temperature observed in western waters (Figure 1.1 and Figure 1.2).

15 ICES WGNSDS report a b Figure 1.1. Difference of bottom temperature ( C) in the Rockall Bank area in spring 2005 from temperature in 2002 (a), 2003 (b) and 2004 (c). c

16 6 ICES WGNSDS report Temperature, C Year 1 2 Figure 1.2. Yearly mean temperature in the areas west of the British Islands in : 1 - Rockall Bank area, N W (surface temperature in January-March), 2 - west of the Porcupine Bank, N W (temperature from m in March-April) Impacts of Fisheries on the Ecosystem ICES has advised on the occurrence of cold-water corals in the North East Atlantic for the past two years. It has also advised that should managers wish to protect these habitats from the effects of fishing, the only effective way to do this is by closing them to all damaging fishing gear. In Subarea VI, one such area has been closed by fishery managers: the Darwin Mounds. This area lies to the south of the Wyville Thomson ridge (to the northeast in Figure 1.3). The Darwin Mounds have been impacted by towed bottom-fishing gear (ICES, 2002). Figure 1.3. Distribution of cold-water coral records within ICES Subarea VI (from ICES, 2003). Not all of the records of cold-water coral in Figure 1.3 are of reefs: some records are of individual fragments trawled or dredged up from the seabed. Accurate determination of the existence and location of reefs requires either remote sonar surveys or visual inspection, either using cameras or manned submersibles, coupled with accurate geo-referencing of the seafloor. In Subarea VI, reefs have been found in UK internal waters to the east of Mingualay in the Outer Hebrides of Scotland (ICES, 2004), on the Rockall Bank (Figure 1.4), particularly on the north-western and south-eastern parts of the Bank (ICES, 2002; 2003). On the southeast Rockall Bank, the coral reefs are associated with large carbonate mounds (the Logachev Mound province) and are particularly well developed. Tangle nets and trawl scar marks have been observed in these reefs (ICES, 2003).

17 ICES WGNSDS report Figure 1.4. The distribution of coral reefs on Rockall Bank from fishermen s records (J. Hall- Spencer, pers comm.). The cross-hatched areas indicate the presence of Lophelia reefs (From ICES, 2003). Both the UK and Irish governments have initiated processes that may, in due course, lead to some of these reefs (and other areas if found suitable) being designated as protected areas under European legislation. It seems very likely that if such sites are designated, fisheries legislation will be needed to help protect them. In the absence of designation, fisheries measures can also be taken to prevent such damage under the Common Fisheries Policy. Outside the European fishing zone (in the high seas to the west of Rockall), no formal protection measures seem possible yet. Further information needs to be gathered on the location of cold-water coral habitats (and other sensitive benthic habitats) and on the effort being applied by fisheries in these areas, disaggregated on a fine scale. 1.5 Description of Fisheries AMAWGC 2005 (ICES 2005) reported that WGFTFB would update the descriptions of mixed fisheries and fishing practices for review by assessment WGs. Unfortunately updated descriptions were not available to the WGNSDS from WGFTFB. WGNSDS therefore reviewed the fisheries descriptions made by ACFM in October 2004 (ICES 2004) Fisheries to the West of Scotland and Rockall The main fleets operating in Division VIa include the mixed roundfish otter trawl fleet, the Nephrops otter trawl fleet, the otter trawl fleet targeting anglerfish, megrim, and hake, and the fleet targeting saithe and/or deep-sea species. To a large extent, the roundfish fishery in Division VIa is an extension of the similar fishery in the North Sea. The demersal fisheries in Division VIa are predominantly conducted by otter trawlers fishing for cod, haddock, anglerfish, and whiting, with bycatches of saithe, megrim, and lemon sole. The majority of the vessels in the demersal fishery are locally-based Scottish trawlers using light-trawls, but trawlers from Ireland, Northern Ireland, England, France, and Germany also

18 8 ICES WGNSDS report 2006 participate in this fishery. The importance of Scottish seiners targeted mainly at haddock has been declining in recent years as many of these vessels have been converted to trawlers. Part of the fleet of light trawlers has diversified into a fishery for anglerfish that has been expanding into deeper water off the northern coast of Scotland. Bycatches in this fishery include megrim, ling, and tusk. About 200 Scottish trawlers also take part in the fisheries for Nephrops on inshore grounds. In recent years Irish vessels have also been targeting Nephrops in Division VIa, mainly on offshore grounds. These Nephrops vessels also land smaller quantities of haddock, cod, whiting, and small saithe, but discard large amounts of whiting and haddock. The development of a directed fishery for anglerfish has led to considerable changes in the way the Scottish fleet operates. Part of this is a change in the distribution of fishing effort; effort in the roundfish fisheries has shifted away from the traditional inshore areas to more offshore areas and deeper waters. The expansion in area and depth-range fished has been accompanied by the development of specific trawls and vessels to exploit the stock. These vessels mainly use large twin-rig otter trawls with >100-mm mesh. A smaller Irish fleet also targets anglerfish, megrim, and hake on the Stanton bank with 90-mm to 100-mm mesh. This fleet has declined in numbers in recent years. The fishery for anglerfish has expanded into deeper waters with an associated increase in catches. The expansion of this fishery has been further accelerated by the diversion of fishing effort from other stocks subject to more restrictive quotas in recent years and by market opportunities. A gillnet fishery has developed on the continental slopes to the West of the British Isles, North of Shetland, at Rockall and the Hatton Bank. A preliminary investigation of this fishery suggests high levels of gear loss, widespread dumping of netting, high catch & discarding levels (particularly of monkfish), and a lack of effective management (see WD18: Shelf edge and deepwater fixed net fisheries). These fisheries are occurring in areas believed to have been a refuge for adult anglerfish, increasing the vulnerability of the stock to overexploitation. Immature fish are subjected to exploitation for a number of years prior to first maturity. The larger Scottish and Irish trawlers fish for haddock at Rockall when opportunities arise for good catches from the Division VIb stock. Vessels from the Russian Federation have fished for haddock and other demersal species at Rockall since 1999 when part of the Bank was designated as being in international waters. Although young saithe are caught by coastal trawlers in Subarea VI, the fishery for saithe essentially takes place on the shelf edge to the west and northwest of Scotland. Traditionally, this fishery has largely been operated by the larger deep-sea French trawlers. However, the number of these vessels has declined in recent years. Since the late 1980s, some of these vessels diverted their activity toward deep-sea species, notably orange roughy, and some medium-sized trawlers also participate in the fishery for deep-sea species during summer in some years. The pelagic fishery for herring is mainly operated by UK, Dutch, and German vessels in the north, and by Irish vessels in the south. Substantial misreporting of catches from the North Sea and between the northern and southern stocks occurred in the past, but UK licensing regulations are thought to have reduced misreporting since In recent years TACs for the northern stock have not been restrictive, presumably because of low effort and a weak market. The Clyde herring fishery has declined sharply in recent years as the stock has suffered from a series of low recruitments. Recent TACs have not been taken and the catches have been less than t since 1991.

19 ICES WGNSDS report There is a directed trawl fishery for mackerel and horse mackerel in the area. The mackerel fishery mainly takes place in the fourth and first quarter of the year, when the mackerel is returning from the feeding area to the spawning area. The horse mackerel is mainly fished in the second half of the year. In addition, there are fisheries for blue whiting in the area. The industrial fisheries in Division VIa are much smaller than in the North Sea. The Scottish sandeel fishery started in the early 1980s, peaking in 1986 and It is irregular, depending on the availability of the resource and of processing facilities at Shetland, Denmark, and the Faroes. Bycatches in this fishery are very small. The Norway pout fishery is conducted mainly by Danish vessels. Fisheries interactions to the West of Scotland and Rockall Demersal fisheries in the area are mixed fisheries, with many stocks exploited together in various combinations in different fisheries. Roundfish are caught in otter trawl and seine fisheries, with a 120-mm minimum mesh size that comprises mixed demersal fisheries with more specific targeting of individual species in some areas and/or seasons. Cod, haddock, and whiting form the predominant roundfish catch in the mixed fisheries, although there can be important bycatches of other species, notably saithe and anglerfish in the deeper water and of Nephrops on the more inshore Nephrops grounds. Static gear fisheries with mesh sizes generally in excess of 140 mm are also used to target cod. Saithe are mainly taken in a directed trawl fishery in deeper water along the shelf in Subarea VI. There is thought to be little bycatch of other demersal species associated with the directed fishery. Large Nephrops fisheries take place in discrete areas that comprise appropriate muddy seabed sediment. Targeted Nephrops fisheries on these grounds are taken predominantly in trawls with mesh sizes of less than 100 mm using single- or multiple-rig trawls. Nephrops fishing grounds are mainly inshore grounds although there are smaller offshore fisheries at Stanton Bank and west of the Hebrides. The bycatch and discarding of other demersal species in the Nephrops fisheries is highly variable. There are trawl and gillnet fisheries targeting hake and anglerfish and otter trawl fisheries targeting hake, megrim, and anglerfish in Subarea VI. The catch of other demersal species associated in these fisheries is uncertain. There is an international fishery targeting haddock, grey gurnards, and other species at Rockall using small mesh. Successful application of TACs for this stock would require that there is a simple relationship between recorded landings and effort exerted. This assumption is unlikely to be true for Rockall haddock especially when coupled with ways of evading TACs including misreporting, high-grading, and discarding. In the case of Rockall haddock these may occur to a large extent due to the remote nature of the fishery and the processing of catches at sea by some fleets. Direct effort regulation is therefore suggested as a means of controlling fishing mortality on Rockall haddock Fisheries in the Irish Sea The majority of vessels in the Irish Sea target Nephrops with either single- or twin-rig otter trawls. These vessels use either 70-mm diamond mesh with an 80-mm square mesh panel or an 80-mm diamond mesh in their codends, and (by regulation) their landings must consist of at least 35% Nephrops by live weight. These vessels have bycatches of whiting (most of which are discarded) and haddock, cod, and plaice. Twin-rig otter trawl were first introduced in the early 1990s. Recent studies show that the use of twin-rigs increases the proportion of

20 10 ICES WGNSDS report 2006 roundfish bycatch in Nephrops fisheries compared with single-rig otter trawls. Nephrops catches are highly seasonal with the highest Nephrops catches in the summer months. Catch rates are also dependent on tidal conditions, with higher catches during periods of weak tide. The roundfish fisheries in the Irish Sea are conducted primarily by vessels from the UK and Ireland. A Northern Irish semi-pelagic trawling for cod and whiting developed in the early 1980s. As the availability of whiting declined this fleet switched to mainly targeting cod and haddock. Irish, Northern Irish, and English and Welsh otter trawlers target plaice, haddock, whiting, and cod, with smaller bycatches of anglerfish, hake, and sole. Some Irish vessels participate in a fishery for rays in the southern Irish Sea. Since 2001, these trawlers have adopted mesh sizes of mm and other gear modifications, depending on the requirements of recent EU technical conservation regulations and national legislation. Fishing effort in the semi-pelagic effort increased rapidly between the early 1980s and early 1990s before decreasing somewhat in the mid-1990s. Fishing effort in the England and Wales otter trawl vessels longer than 12m declined rapidly after 1989, and from 1992 to 1995 was about 40% of the effort reported in the 1980s, although it has increased slightly in recent years. There has been a declining trend in fishing effort for Northern Irish otter trawlers also since the early 1990s. Fishing effort for Irish otter trawlers has declined in recent years as many vessels switched from targeting roundfish to Nephrops. There is also a beam trawl fishery which takes place mainly in the eastern Irish Sea with vessels from Belgium, Ireland, and the UK. This fishery mainly catches sole with important bycatches of plaice, rays, brill, turbot, anglerfish, and cod. The fishing effort of the Belgian beam-trawl fleet varies in response to the catch-rates of sole in the Irish Sea relative to catchrates in other areas in which the fleet operates. Fishing effort peaked in the late 1980s following a series of strong year classes of sole, but is presently only about 60% of the peak value. The other gears employed to catch demersal species are gillnets and tangle nets, notably by inshore boats targeting cod, bass, grey mullet, sole, and plaice. The main pelagic fishery in the Irish Sea is for herring. In recent years, it has been predominantly operated by one pair of trawlers from Northern Ireland. The size of this fleet has declined to a very low level in recent years. There are also a number of inshore fisheries in the Irish Sea that target stocks not currently assessed by ICES. These include pot fisheries for crab, lobster, and whelk, hydraulic dredge fisheries for razor clams, and dredge fisheries for scallops. Decommissioning at the end of 2003 permanently removed 19 out of 237 UK demersal vessels that operated in the Irish Sea, representing a loss of 8% of the fleet by number and 9.3% by tonnage. Of these vessels, 13 were vessels that had used demersal trawls with mesh size >=100mm and had more than 5% cod in their reported landings. The previous round of decommissioning in 2001 removed 29 UK(NI) Nephrops and whitefish vessels and 4 UK(E&W) vessels registered in Irish Sea ports at the end of Of these, 13 were vessels that used demersal trawls with mesh size >=100mm and had more than 5% cod in their reported landings.

21 ICES WGNSDS report Fisheries in other areas covered by the WGNSDS The fisheries in other areas covered by the WG are described in the relevant stock sections. 1.6 Enumeration of Capacity and Effort The WG was unable to enumerate the capacity of fishing fleets in each country as data were not available to the WG. For the Irish Sea long-term data on fishing effort were available to the WG for the UK(E&W) otter trawl and beam trawl fleets, the Belgian beam trawl fleet, and the UK(NI) semi-pelagic and single otter-trawl fleet (Table 2.1). The UK(NI) data include only trips in the main fishing areas but represent the majority of the effort recorded for the fleets. A general decline in reported fishing effort has occurred since the 1990s (Table 1.2 and Figure 1.5).

22 12 ICES WGNSDS report 2006 Table 1.2 Effort in the Irish Sea of >40' UK (E&W) otter trawlers, French otter trawlers, UK (NI) otter and pelagic trawlers, UK (E&W) beam trawlers and Irish otter trawlers. Year UK (E&W) otter 4 UK (NI) otter 5 UK (NI) pelagic 5 UK (E&W) beam 4 Belgium beam Ireland otter ,401 6, ,642 16, ,161 14, ,733 16, ,337 15, ,881 13, , , ,864 1,702 13, ,026 4,283 20, ,063 6,433 26, ,194 5,503 21, ,088 2,770 18, , ,687 36,173 4,136 13, , ,017 37,469 7,407 21, , ,473 46,515 17,031 38, , ,901 67,766 21,997 43, , ,191 69,375 18,564 32, , ,636 84,354 25,291 36, , ,518 93,471 31,033 38, , ,828 86,385 25,838 15, , ,226 97,363 23,399 23, , ,323 74,014 21,503 24, , ,705 73,778 20,145 31, , ,025 52,773 20,932 27,100 80, , ,418 53,083 13,320 22,200 64, , ,612 55,863 10,760 29,300 92, , ,088 61,153 10,386 23,800 93, , ,990 72,859 11,016 22, , , ,117 46,412 6,275 18,200 82, , ,418 50,302 12,495 28,500 77, , ,616 57,754 8,000 36,200 77, , ,551 61,539 14,000 23,000 73, ,460 n/a n/a 7,400 35,400 72,507 1 Weighted mean deseasonalised CPUE over ICES rectangle, GRT corrected (Kg/h) Ire otter 2003 revised 2 De-seasonalized CPUE 3 Ratio of total landings to total hours fished in main fishing area: SINGLE RIG TRAWLS ONLY 4 Total aggregate hours fished, corrected for vessel GRT 5 Total aggregate hours fished in main fishing area: SINGLE RIG TRAWLS ONLY n/a = not available

23 ICES WGNSDS report Figure 1.5 Trends in effort for commercial tuning fleets in the Irish Sea. All series are expressed relative to their series mean. Effort scaled to mean UK (E&W) otter UK (NI) otter UK (NI) pelagic UK (E&W) beam IRL otter Figure 1.5. Trends in effort for commercial tuning fleets in the Irish Sea. All series are expressed relative to their series mean. A more detailed breakdown of fishing effort by country and gear type (where available) is given in Table 1.3, based on reported hours fished, with power correction in some cases. Fishing effort of UK(NI) pelagic trawlers declined following the introduction of the cod closure in 2000 (Figure 1.6), coincident with an increase in twin Nephrops otter trawl effort due to vessels switching between trawling methods. The fishing effort of single-rig otter trawlers (UK(NI) light otter trawls and single Nephrops trawls, UK(E&W) otter trawls and Irish otter trawls) has declined since 1997 (Figure 1.6). The impact on these changes on fishing mortality of stocks will depend on the partial fishing mortality exerted by each fleet and any changes in species targeting or tie-ups that may have occurred. Decommissioning of UK otter trawl and pelagic trawlers in 1999 and 2001 will have contributed to the trends in effort.

24 14 ICES WGNSDS report 2006 Table 1.3 Relative trends in fishing effort of fishing fleets operating in the Irish Sea, measured as annual hours fished without power correction (unless noted). Values are given relative to 1999, the last year before introduction of the cod closure in Year NILTR NIPel NI TNT NI SNT NI Sei NI PTD IR OTB UK(EW) OTB PC UK(EW) BT PC Belgium BT PC IR-BT ,434 56,529 20, , ,178 39,886 10,760 29,300 9, ,228 61,803 29, , ,533 36,902 10,386 23,800 11, ,725 73,278 29, ,117 1, ,275 22,903 11,016 22,100 14, ,746 47,604 41, ,921 2, ,690 26,967 6,275 18,200 11, ,073 51,090 35, , ,665 77,541 32,960 12,495 28,500 13, ,327 57,854 26,821 98, ,250 77,863 24,760 8,000 36,200 17, ,897 61,899 31, ,726 1,104 1,189 73,854 23,850 14,000 23,000 18, ,702 35,551 35,281 93,544 1, ,507 23,460 7,400 35,400 14,188 PC: With Power Correction. NILTR UK(NI) light otter trawl (all mesh sizes; predominantly 80mm). NIPel UK(NI) midwater demersal (mainly 80mm mesh prior to 2000; 100mm+ mesh after 2000). NI TNT UK(NI) twin Nephrops trawl (70-80mm). NI SNT UK(NI) single Nephrops trawl (70mm). NI Sei UK(NI) seine net (80-100mm+ prior to 2000, 100mm + after 2000). NI PTD UK(NI) pair trawl demersal (mainly 100mm+). IR(OTB) Ireland otter trawls (single and twin Nephrops (70-80mm) and whitefish otter (100mm+)). UK(EW)OTB UK(E&W) otter trawls (single Nephrops (70-80mm) and whitefish otter (80-100mm+)). UK(EW) BT UK(E&W) beam trawl (80mm). Belgium BT Belgium beam trawlers (80mm). IR BT Irish beam trawlers (80mm). Figure 1.6 Relative trends in fishing effort of fishing fleets operating in the Irish Sea, measured as annual hours fis with or without power correction. Values are given relative to 1999, the last year before introduction of the cod closure in NIPel 2.00 NILTR 2.00 UK(EW) OTB PC NI TNT 2.00 NI SNT 2.00 IR OTB UK(EW) BT PC 2.00 Belgium BT PC 2.00 IR-BT NI PTD 2.00 NI Sei Figure 1.6. Relative trends in fishing effort of fishing fleets operating in the Irish Sea, measured as annual hours fished with or without power correction. Values are given relative to 1999, the last year before introduction of the cod closure in 2000.

25 ICES WGNSDS report Data on kw-days were not available for all national fleets, hence the WG was not able to evaluate the change in fishing effort relative to days-at-sea restrictions imposed since However, in the Irish Sea there is little evidence for a reduction in hours fished by gear type between 2002 and 2003, although there was a decline in pelagic trawl effort from 2003 to To the west of Scotland reported effort in the Scottish light trawl fleet has declined steadily from 35,698h in 2001 to 9357h in The Scottish seine fleet reported declines in effort too and the 2003 figure (2370h) is the lowest in the series. The Scottish Nephrops fleets reported a more gradual decline in effort with 256,000h recorded in 2003 as opposed to 258,000h in Due to Scottish reporting problems, however, these effort data may be underestimates. The effort in Sub-Area VI exerted by Irish otter board trawlers has shown a steady decline since 1997: Irish otter trawl effort Year ('000 h) VIa VIb Information on the number of Scottish vessels operating in the Division VIa cod recovery zone to have been decommissioned between 2001 and 2004 was available at this working group. A total of 298 Scootish vessels >10m were operating in of these vessels were decommissioned by the end of 2004 (30.2%). The effort of some fleets fishing for Anglerfish is discussed in relevant stock sections. 1.7 Regulations TAC Regulations The Regulations specifying Total Allowable Catches (TAC) by species and management area for stocks assessed by WGNSDS are as follows:

26 16 ICES WGNSDS report 2006 STOCK COUNCIL REGULATION (EC) NO: MANAGEMENT AREA 2848 / TAC 2555 / TAC 2341 / TAC 2287 / TAC Cod Vb α, VI, XII, XIV 3,700 4,600 1, / TAC VIIa 2,100 3,200 1,950 2,150 2,150 Megrim Vb α, VI, XII, XIV 4,360 4,360 4,360 3,600 2,880 Anglerfish IIa α, IV α 14,130 10,500 7,000 7,000 10,314 Vb α, VI, XII, XIV 6,400 4,770 3,180 3,180 4,686 Haddock Vb, VI α, XII, XIV 13,900 14,100 8,675 ~ ~ Vb, VIa ~ ~ ~ 6,503 7,600 VIb α, XII, XIV ~ ~ ~ VII, VIII, IX, X, 12,000 9,300 8,185 9,600 11,520 CECAF α VIIa β 2,700 1, ,500 1,500 Whiting Vb α, VI, XII, XIV 4,000 3,500 2,000 1,600 1,600 VIIa 1,390 1, Plaice VIIa 2,000 2,400 1,675 1,340 1,608 Sole VIIa 1,100 1,100 1, Nephrops VI, Vb α 11,340 11,340 11,340 11,300 12,700 Nephrops VII 18,900 17,790 17,790 17,450 19,544 α : European Community waters, β : Within the limits of the VII, VIII, IX, X and CECAF TAC, no more than the quantity stated may be taken in Division VIIa Other Regulations Area Closures Due to the depleted state of the stock and following the advice from ICES, a recovery plan for cod in the Irish Sea was introduced in Commission Regulation (EC) No 304/2000 established emergency closed areas to fishing for cod between 14 February and 30 April in the western and eastern Irish Sea to protect spawning adults at spawning time (Figure 1.7). Council Regulation (EC) 2549/2000, which came into force on 1 January 2001, with amendments in Council Regulation (EC) No 1456/2001, of 16 July 2001, established additional technical measures for the protection of juveniles. The closed area in the Irish Sea and additional technical regulations were extended to 2001 in Council Regulation (EC) 300/2001 and to 2002 in Council Regulation (EC) 254/2002. The main difference in the recovery measures for 2002, 2003 and 2004 from those of 2001 is that a closed area remained only in the western Irish Sea time (Figure 1.7). Derogations have existed for fleets targeting Nephrops in all years.

27 ICES WGNSDS report Figure 1.7. Maps of the Irish Sea (VIIa) closed areas for The closed area is shaded red and the area open to Nephrops derogations is shaded green. Emergency measures were enacted in 2001 for the west of Scotland, consisting of area closures from 6 March 30 April, in an attempt to maximise cod egg production. These measures were retained into 2003 and A new closed area was implemented to the west of Scotland in 2004 under Council Regulation (EC) No 2287/2003. In the west of Scotland there have been unilateral closures by Ireland of a traditional fishery for juvenile cod off Greencastle, Co. Donegal (Figure 1.8). From mid-september 2003 to midfebruary 2004 (Irish Statutory Instrument (SI) No. 431 of 2003) closed the area. In December 2003 the closed area was extended along its eastern edge by amendment to the Statutory Instrument (SI No. 664 of 2003). Whilst the initial closure period officially ended in midfebruary 2004, fishermen in the local trawl fleet imposed a voluntary exclusion to trawling within the boundaries of the closed area as described in SI 664 of These fishermen submitted signed declarations effectively banning trawling in the area from February 15th to July 1st A new Statutory Instrument (SI No. 670 of 2004) reinstated the closed area from 1st November 2004 until 14th February These closures were instigated by the local fishing industry to allow an assessment of seasonal closure as a potential management measure. Over 11,500 cod have been tagged and released during the closures. Most of the cod catch during the closed period is normally taken in the fourth quarter. During % of the Irish catch weight of cod in VIa (61% by number) was taken in the fourth quarter. The closure is expected to have reduced the Irish fishing mortality on cod that would otherwise have occurred in 2003 and As the Greencastle codling fishery is a mixed demersal fishery, any benefits Flowing from the closure are likely to extend to other demersal stocks.

28 18 ICES WGNSDS report 2006 Figure 1.8. Location of the area closed by Irish Statutory Instrument in and Effort Limitation Annex XVII to Council Regulation (EC) No 2341/2002 regulated fishing effort to the West of Scotland. The extent of effort limitation varied for particular gears. The maximum number of days in any calendar month for which a fishing vessel may be absent from port to the West of Scotland in 2003 was: 9 days for demersal trawls, seines or similar towed gears of mesh size 100 mm except beam trawls, 25 days for demersal trawls, seines or similar towed gears of mesh size between 70 mm and 99mm except beam trawls, and, 23 days for demersal trawls, seines or similar towed gears of mesh size between 16 mm and 31 mm except beam trawls. The Regulation included a provision for additional days to be allocated on the basis of the achieved results of decommissioning programmes. A Commission Decision (C(2003) 762) in March 2003 allocated additional days absent from port to particular vessels and Member States. United Kingdom vessels were granted 4 additional days per month (based on evidence of decommissioning programmes). An additional two days was granted to demersal trawls, seines or similar towed gears (mesh 100mm, except beam trawls) to compensate for steaming time between home ports and fishing grounds and for the adjustment to the newly installed effort management scheme. Monthly effort limitation was extended to the Irish Sea (and other cod recovery areas) under Annex V to Council Regulation (EC) No 2287/2003. The restrictions for the West of Scotland and Irish Sea (per month) in 2004 were: 10 days for demersal trawls, seines and similar towed gears with mesh size >= 100mm, 14 days for beam trawls of mesh size >= 80mm and static demersal nets, 17 days for demersal longlines,