14 NEPHROPS IN DIVISION VIIa

Transcription

1 636 ICES WGNSDS report NEPHROPS IN DIVISION VIIa Nephrops in Managem ent Ar ea J Nephrops were previously assessed by WGNEPH on the basis of population distribution, and defined as separate Functional Units. The Functional Units (FU) are defined by the groupings of ICES statistical rectangles given in Table The Functional Unit is the level at which the WG collects fishery data (quantities landed and discarded, fishing effort, CPUEs and LPUEs, etc.) and length distributions, and at which it performs analytical assessments. Nephrops from the north of 53 o N of Division VIIa form two Functional Units, Irish Sea East (FU14) and Irish Sea West (FU15). These Functional Units are combined to form Management Unit J. The TAC area as defined by ICES comprises of an aggregation of Management Units M, A & J (ICES area VII). This stock was last assessed by WGNEPH The Fishery ICES advice applicable to 24 and 25 ICES advice for 24 Fisheries on Nephrops should demonstrate that they are capable of catching Nephrops without significant by-catches (including discards) of cod. This demonstration should be in real time through independent monitoring or other credible and transparent means. If this requirement is met, then there is no basis to revise the advice given previously, and therefore ICES recommends that the TAC from this Management Area in 24 and 25 be kept to the level recommended in 21, i.e. 955 t. ICES also notes that this Management Area is within a much larger TAC area (Sub-area VII), and that a single TAC set for the whole Sub-area will not result in balanced exploitation. In an attempt to resolve this problem, ICES suggests a separate Nephrops TAC for Division VIIa, as is done for several finfish stocks (such as cod, whiting, plaice and sole). ICES advice for 25 Single Stock Exploitation Boundaries: There is no basis to revise the advice given previously of a TAC from this Management Area in 24 and 25 be kept at the level recommended in 21, i.e t. Advice on the exploitation of this stock in 24 is presented in the context of mixed fisheries and is found in Section (of ACFM Report, October 24) ICES also notes that this Management Area is within a much larger TAC area (Sub area VII), and that a single TAC set for the whole Sub area will not result in balanced exploitation. In an attempt to resolve this problem, ICES suggests a separate Nephrops TAC for Division VIIa, as is done for several finfish stocks (such as cod, whiting, plaice, and sole). 636

2 ICES WGNSDS report Managem ent applicable in 24 and 25 Management area J falls with a larger TAC area for management purposes. The table below gives the ICES advice and basis as provided for each Management Area in 23 the TAC area as a whole in 23. The table also gives the TACs in 24 and 25 for all of VII. The TAC was increased by 12% in 25 but this was not based on scientific recommendations. Management Area Functional Units ICES advice for MA in VII Basis of ICES advice in 23 TAC 24 TAC 25 WG-MA J 14, 15 9,55 Average landings WG-MA L 16, 17, 18,19 3,3 Landings for FU 16 constrained to recent low (2-22 = 1,1 t) Average Landing for other FUs =2,2 t WG-MA M ,6 Average landings Sub-Area VII 14 to 22 17,45 17,45 19,544 In 23 and 24 the main fleets targeting Nephrops include Nephrops directed single-rig and twin-rig otter trawlers operating out of ports in UK (NI), UK (E&W) and Ireland. Details of all regulations including effort controls in place are provided in Section 1.7. These regulations incorporate a system of 'mesh size ranges' for each of which has been identified a list of target species. In effect, nets in the 7-79 mm mesh size range must have at least 35 % of the list of target species (which includes Nephrops) and the 8-99 mm mesh size range requires at least 3 % of the list of target species. A square mesh panel (SMP) of 8 mm is required for 7-79 mm nets in the Irish Sea. Vessels using twin-rig gear in the Irish Sea must comply with a minimum mesh size of 8 mm (no SMP is required for nets with 8 mm meshes and above). In addition to Nephrops measures the cod spawning areas of the Irish Sea are closed to whitefish directed vessels from 14 February to 3 April as part of the Irish Sea cod recovery plan. There is a derogation for Nephrops vessels during this closure. Other Nephrops conservation measures in the Irish Sea are a minimum landing size of 2 mm CL length (equivalent to 37 mm tail length or 7 mm total length) Irish Sea East (FU1 4) The fishery in 24 The historical development of the fishery for Nephrops in FU14 is described in the Stock Annex. Over the last 1 years UK vessels landed most of the international landings (up to 97%) although Irish vessels increased their share of the landings up to 35% in 22 (Table 14.2, Table 14.3 & Figure 14.1). In 24, most of the landings were made into England with a high proportion of these landings (59 % of the directed landings and 52% of the total landings) being made by visiting Northern Ireland vessels. 637

3 638 ICES WGNSDS report Catch data Official Catch Statist ics Official landings as reported to ICES from Management Area J are presented in Table 14.2 and are incomplete for Revision to catch data The last assessment of Management Area J Nephrops stocks was conducted by WGNEPH in 23. Some minor revisions have been made to 22 catch data Quality of the Catch dat a The TAC for Division VIIa Nephrops forms part of the larger TAC Area VII, which has remained between 1779 and 23 tonnes since This advice was provided on the basis of historical landings owing to the inability to conduct appropriate catch predictions. Individual vessel quotas have become restrictive leading to under reporting of landings Com m ercial catch- effort data and research vessel surveys Irish effort showed a marked fluctuation over the period and high LPUE (Table 14.6). The UK LPUE series (Table 14.7) is based on a combination of directed Nephrops voyages by English and Welsh vessels landing to Fleetwood and Whitehaven, where the weight of Nephrops landed is more than 25 % of the total landing, and all trips by visiting Northern Irish vessels which target Nephrops. Quarterly effort plots show a predominance of effort in the 2 nd and 3 rd quarters (Figure 14.2). Since a reduction in effort during the 3 rd quarter of 1998, the seasonal pattern returned to 'normal' until the poor season in 22. Since then, effort in both the 2 nd and 3 rd quarters has been at least 2% below the mean. Effort in the 3 rd quarter has been particularly stable since 22 at around 5 trawling hours in contrast with the period from 1991 to 21 when it fluctuated between extremes of 2.1 and 115. The combined LPUE has fluctuated between 17 and 27 kg/hour trawling in the last 1 years with the lowest and the highest LPUE figure occurring in 23 and 24 respectively (Figure 14.2). High male LPUE usually occurs in the 1 st, 2 nd and 3 rd quarters, while females have the highest LPUEs in the 3 rd quarter, between hatching and spawning. LPUEs for males and females < 35 mm CL (Figure 14.3) appear to exhibit the same trends fluctuating around averages of 5.5 and 4.5 kg/hour trawling respectively. Both series show the lowest LPUEs in 23. The LPUE of the larger males (>35mm) shows a slight increase since 22. The mean size of females in the 3 rd quarter is consistently higher than in other quarters. In the third quarter, females on average make up more than 5% of the landings when in any other quarters they make up on average 2% of the landings. The annualised proportion of females in the landings shows a very similar pattern of variation to effort in the 3 rd quarter (Figure 14.1) Length at Age com posit ion and m ean weights- at- age Quarterly discard distributions from England & Wales for the years 1995 to 1999 were estimated by using the discard LFDs for the two preceding and the two following years. 638

4 ICES WGNSDS report Apparent differences between catch LFDs and discard practices in 1992 to 1994 and 1999 to 2 resulted in 21 and 22 data being used to estimate the LFDs for missing years. Two more years of catch and landings sampling by England & Wales provided further catch compositions to add to the data series. Age compositions were generated using the L2AGE program. All length data and input data are available on the stock files Natural m ortality and m aturity at age Natural mortality in males and immature females was assumed to be.3 and for mature females it was taken as.2 as in previous years. All males were assumed to be mature and females were considered mature at age 2: Proportion of F and M before spawning were both set to., in order to generate abundance (and hence SSB) estimates dated to January 1 st. Growth parameters for age slicing are as follows: Males; L = 6mm, k =.16 Immature Females; L = 6mm, k =.16 Mature Females; L = 56mm, k =.1, Size at maturity = 24mm Catch- at- age- analyses Section 2.7 outlines the general approach adopted at this year s WG meeting Dat a screening and ex ploratory runs Commercial catch data Although levels of market and discard sampling in the Irish Sea East were sustained during 23 and 24 concerns have been raised at both WGNEPH and WGNSDS about the implications of the use of the knife edge slicing technique for catch at age analysis of the resulting year classes. The increase in variability in length at age for older individuals may lead to a number of real ages being included within a sliced age, leading to an overestimation of F Survey data There were no fishery independent survey data available for this Functional Unit Exploratory assessment runs XSA A trial single fleet assessment was carried out, using UK data from The Lowestoft VPA program was run on 'age groups' generated by slicing the length distributions with the L2AGE program. Tuning of the VPA was carried out with Inputs are detailed in Table

5 64 ICES WGNSDS report 25 and the VPA was tuned with the available commercial CPUE series for the UK English, Welsh and Northern Ireland Nephrops directed trawl effort data adjusted to international landings. After exploratory runs optimal settings were chosen and a final run completed. The results of this assessment together with the XSA diagnostics are provided in the stock files. Given the concerns of the WG on the appropriateness of the commercial CPUE tuning fleet, the Official landings and effort data, the implications of the slicing procedure and the validity of a dynamic pool model for Nephrops, it was decided not to present an XSA assessment Final assessment run The WG s rejection of the exploratory XSA analysis means that no final assessment is presented Reference points No reference points have been determined for this Nephrops stocks Management considerations This is discussed in Section 14.4 in relation to Management Area J Irish Sea West (FU15) The Fishery General information on the fishery can be found in Section and in the stock files Catch data Total international Nephrops landings reported from FU 15 in 23 and 24 were 6921 t and 729 t respectively, which is a slight increase the 22 landings of 6914 t (Table 14.1 & Figure 14.5). Republic of Ireland landings peaked at 4582 t in 1999 and dropped to a provisional 2734 t in 24. Landings by UK vessels from this FU were 4237 t and 4462 t for the two years, which is over 6 % of the international landings in these years (61.2% and 61.9%). Northern Ireland landings represented over 96 % of the total UK landings from this FU. A major factor contributing to the decline in Northern Ireland effort is the decommissioning exercise described in the stock files Official Catch Statist ics Official landings as reported to ICES from Management Area J are presented in Table 14.2 and are incomplete for Revision to catch data The last assessment of Management Area J Nephrops stocks was conducted by WGNEPH in 23. Some minor revisions have been made to 22 catch data. 64

6 ICES WGNSDS report Quality of Catch data The TAC for Division VIIa Nephrops forms part of the larger TAC Area VII, which has remained between 1779 and 23 tonnes since This advice was provided on the basis of historical landings owing to the inability to conduct appropriate catch predictions. There is some evidence of under reporting in this fishery and individual vessel quotas have been restrictive Com m ercial catch- effort data and research vessel surveys CPUEs and LPUEs for the Northern Ireland fleet have remained relatively constant since 1995 with the slight dip in 2 and 21. The lowest CPUE over the reference period ( ) was in 21. Republic of Ireland CPUE data available for Nephrops from 1995 showed steady increase followed by a slight drop since 1999 and stabilization apart from a peak in 22 (Table & Figure 14.4). The mean sizes of Nephrops in the catches of both the Northern Ireland and the Republic of Ireland fisheries have fluctuated without obvious trend throughout the time series ( ) (Figure 14.4). A more detailed analysis of effort data and CPUEs by sex for is shown in Figure It was not possible to update this figure for 23 and 24 due to the absence of sample data from Northern Ireland. Analysis of quarterly Northern Ireland and Irish effort data showed effort to be high during the summer months when female Nephrops are most available for capture. Annual CPUEs are therefore only comparable if the seasonal distribution of effort is constant, as discussed by SGNEPH94. Analysis of CPUE by sex and quarter for large (> 35 mm CL) and small (< 35 mm CL) Nephrops (Figure 14.6) demonstrate a scarcity of large female animals, especially in the 1 st and 4 th quarters, when egg-bearing females remain in their burrows to incubate their eggs. Since 23 Ireland and Northern Ireland have jointly carried out and underwater television survey on the main Nephrops grounds in the western Irish Sea. These surveys were based on a randomised fixed grid design. The methods used during the survey were similar to those employed for UWTV surveys of Nephrops stocks around Scotland and elsewhere (See Chapter 13). Northern Ireland has carried out a spring (April) and summer (August) Nephrops trawl surveys since These surveys provide data on catch rates and LFDs from of stations throughout in the western Irish Sea (Figure 14.1) Length at Age com posit ion and m ean weights- at- age The sample numbers of Nephrops caught, landed and discarded (Figure 14.7) were used to calculate total removals at length by raising them to the fleet and international catch for each year of the time series (Ireland, and Northern Ireland ). Removals are defined as landings plus dead discards based upon a discard mortality of 9%. A lack of cooperation by the Northern Ireland industry prevented sampling during 23 and 24. The Irish LFDs were therefore raised to the Northern Ireland and international catch for these years Natural m ortality and m aturity at age Natural mortality in males and immature females was assumed to be.3 and for mature females it was taken as.2 as in previous years. All males were assumed to be mature and females were considered mature at age 2: 641

7 642 ICES WGNSDS report 25 Proportion of F and M before spawning were both set to., in order to generate abundance (and hence SSB) estimates dated to January 1 st. Growth parameters for age slicing are as follows: Males; L = 6mm, k =.16 Immature Females; L = 6mm, k =.16 Mature Females; L = 56mm, k =.1, Size at maturity = 24mm Catch- at- age- analyses Section 2.7 outlines the general approach adopted at this year s WG meeting Dat a screening and ex ploratory runs Commercial catch data Although catch at length and effort data were available for a sub-set of Irish Nephrops trawlers ( ) and for the Northern Ireland fleet ( ) both WGNEPH and WGNSDS have expressed concern about the implications of the use of the knife edge slicing technique for catch at age analysis of resulting year classes. Evidence of under reporting of landings discussed elsewhere in this report also creates problems with raised data. The CPUE and LPUE data will also be affected by under reporting and by changes in catchability over the time series due to changes in efficiency and structure of the fleets Survey data The underwater TV surveys performed in 23 and 24 are presented as the best available information on the Western Irish Sea Nephrops stock. This survey provides a fishery independent estimate of Nephrops abundance. Plots of the standardised burrow densities (numbers/m2) are shown for the 23 and 24 surveys in Figure The results indicate relatively high burrow densities are widespread throughout the survey area. The densities observed are higher than those reported for any other Nephrops stocks where camera surveys have been performed. The spatial pattern show some general similarities however, in 23 highest densities were found in the south-western corner of the grounds whereas in 24 highest densities were found in the northern part of the ground. The exceptionally high densities (>2.5/m 2 ) observed in the 23 survey were not as common in the 24 survey (Figure 14.9). Modal density was slightly higher in 24 than in 23. Relevant metadata and results for the two surveys are summarised in the text table below. Further work is currently underway to more accurately quantify precision and improve the accuracy of these surveys using geostatistics until then the results presented here are preliminary. In addition a further joint survey is planned for August 25. Details of Ireland and UK Northern Ireland underwater TV surveys to date. 642

8 ICES WGNSDS report Mean Density (No./M 2 ) Raised abundance estimate (X1 9 ) Number of Area Surveyed Burrow Year stations (M 2 ) Variance count , , , , Northern Ireland trawl surveys demonstrate no trend in mean size (Figure 14.11) an increasing trend in catch rate (Figure 14.12) and constant recruitment as indicated from the number of animals <2mm CL (Figure 14.13). Similarly there is no trend in the number of large >3mm Nephrops (Figure 14.13) Exploratory assessment runs XSA LFDs time series from Northern Ireland ( ) and the Republic of Ireland fisheries ( ) were combined and raised to provide an 'international' Nephrops size composition. In the absence of Northern Ireland LFDs for the Republic of Ireland lengths were raised to the international catch for these years. Total removals were calculated as landings plus 9 % of the discards, assuming a discard survival of 1 %. The availability of LPUE data for both the Northern Ireland and the Republic of Ireland Nephrops fleets enabled a multi-fleet assessment to be performed as in 23. VPA tuning inputs were obtained by running the L2AGE slicing program with the Northern Ireland data for Similarly, tuning inputs for the Republic of Ireland fishery were obtained by running the L2AGE program on the data for The two tuning data files were merged and used to tune a multi-fleet XSA performed on the age compositions of males and females separately (Table & Table 14). The LFDs of the total male and female removals were sliced into age classes -8 (8 = plus group). Tuning of the VPA was carried out using the XSA options shown in Table and Table The log catchability residuals for both tuning fleet did not show particular trends. A retrospective VPA was performed using the same inputs used in the XSA. The diagnostics provided by this analysis indicated good agreement in early years for recruitment, SSB and Fbar (3-5). There was concern by the WG about the appropriateness of the commercial CPUE tuning fleet, the Official landings and effort data, the implications of the slicing procedure and the validity of a dynamic pool model for Nephrops. It was therefore decided not to present an XSA assessment. The diagnostics and results of the exploratory runs are provided in the Stock file Final assessment run The WG s rejection of the exploratory XSA analysis means that no final assessment is presented for FU Comparison with last years assessment This was the first time a western Irish Sea UWTV survey has been presented to the WG. 643

9 644 ICES WGNSDS report Reference points No reference points have been determined for this Nephrops stocks Management considerations This is discussed in Section 1.4 in relation to management considerations for Management Area J Managem ent Area J Managem ent Considerat ions Evidence of under reporting of landings creates problems with using commercial data for analytical assessments and in TAC recommendations. Despite evidence of under reporting the VIIa Nephrops fisheries have been sustained for over 2 years with similar high levels of fishing effort. There is no evidence from mean size of animals in catches or from more recent trawl survey data that might indicate a problem with these stocks. The previous ICES practice of basing TAC recommendations on reported landings where there is evidence of under-reported landings is not appropriate, as these stocks appear to be sustainable with higher catch rates. As TACs implemented appear not to limit catches it seems more appropriate to manage the Nephrops by effort control rather than by TAC in the short term. In such an effort control management regime it is also important to take into account changes in efficiency, fishing patterns and to document catches and effort accurately. In the absence of analytical catch-based assessments the WG recommend a harvest ratio approach based on UWTV survey data for Nephrops stocks as described in Section Preliminary results of a joint Irish/Northern Ireland UWTV survey indicate that the density of Nephrops on the western Irish Sea grounds are substantially higher than in other areas surveyed. It is important to mention that despite these high densities the mean size of Nephrops in research and commercial catches is also substantially lower than in other areas. The WG concluded that further work is required to quantify the uncertainties in the 23 and 24 surveys before a suitable conservative harvest ratio could be applied for FU15. In addition more recent information will be available before October ACFM since another survey is scheduled for August 25. Previously, ICES has been asked to base advice on the most up to date information therefore the WG propose that the results of all the surveys are provided in a WD to the review group prior to ACFM. 644

10 ICES WGNSDS report Table Nephrops Functional Units and descriptions by statistical rectangle. Functional Unit Stock ICES Rectangles Management Area 14 Irish Sea East 35-38E6; 38E5 J 15 Irish Sea West 36E3; 35-37E4-E5; 38E4 J Table Official catch data Nephrops VIIa as reported to ICES Country Belgium 2 1 France ,539 3,797 2, Ireland 4,682 4,639 3,21 2,84 2, 3,2 2,37 2,614 2,337 3,33 2,156 Isle of Man UK - Eng+Wales+N.Irl. 6,2 6,155 6,85 5,572 5,9 6,3 5,944 6,13 UK - England & Wales UK - N. Ireland 5,188 5,91 5,255 UK Scotland Total Country * Belgium France Ireland 3,695 2,754 4,698 3,621 2,892 2,43 2,846 na Isle of Man UK - Eng+Wales+N.Irl. 7,163 6,316 6,514 5,328 5,213 4,841 4,621 4,953 UK - England & Wales UK - N. Ireland UK Scotland Total ,954 *Preliminary na not available Table Management Area J (Vlla, North of 53 N): Total Nephrops landings (tonnes) by Functional Unit plus Other rectangles, Year FU 14 FU 15 Other Total * * provisional 645

11 646 ICES WGNSDS report 25 Table Management Area J (Vlla, North of 53 N): Total Nephrops landings (tonnes) by country, Year Belgium France Rep. of Ireland Isle of Man UK Total * * provisional Table Irish Sea East (FU 14): Landings (tonnes) by country, Year Rep. of Ireland UK Other countries ** Total * * * 472 * provisional na = not available ** Other countries includes Belgium and Isle of Man 646

12 ICES WGNSDS report Table Irish Sea East (FU 14): Effort ( hours trawling) and LPUE (kg/hour trawling) of Nephrops directed voyages by UK trawlers, Year Effort LPUE * * provisional Table Irish Sea East (FU 14): Effort ( hours trawling) and LPUE (kg/hour trawling) of Nephrops directed voyages by Republic of Ireland trawlers, Year Effort LPUE * * provisional 647

13 648 ICES WGNSDS report 25 Table Irish Sea East (FU 14): Mean sizes (mm CL) of male and female Nephrops from UK vessels landing in England and Wales, Catch Landings Discards Year Males Females Males Females Males Females 1995 na na na na 1996 na na na na 1997 na na na na 1998 na na na na 1999 na na na na na na na na na na na na 24* na na * provisional na = not available Table Nephrops, Irish Sea East (FU14) Commercial fleet tuning series for UK England & Wales Nephrops trawlers, for males and females. Effort (first column) is reported as hours ( s) fished, numbers removed are in thousands. Raising procedures documented in the Stock Annex (section B4). FU14 E IRISH SEA TUNE DATA :EFFORT 1HRS MALES FLEET

14 ICES WGNSDS report FU14 E IRISH SEA FEM TUNE DATA :EFFORT 1HRS 11 FLEET Table Irish Sea West (FU 15): Landings (tonnes) by country, Year Rep. of Ireland Isle of Man UK Other countries ** Total * * provisional 649

15 65 ICES WGNSDS report 25 Table Irish Sea West (FU 15): Catches and landings (tonnes), effort ( hours trawling), CPUE and LPUE (kg/hour trawling) of Northern Ireland Nephrops trawlers, Year Catches Landings Effort CPUE LPUE * * provisional Year Table Irish Sea West (FU 15): Mean sizes (mm CL) of male and female Nephrops in Northern Ireland catches, landings and discards, Catches Landings Discards Males Females Males Females Males Females na na na na na na 24* na na na na na na * provisional na = not available 65

16 ICES WGNSDS report Year Table Irish Sea West (FU 15): Mean sizes (mm CL) of male and female Nephrops in Republic of Ireland catches, landings and discards, Catches Landings Discards Males Females Males Females Males Females na na na na * * provisional na = not available (Qtr 3 & Qtr 4 missing) ** Males and females combined 651

17 652 ICES WGNSDS report 25 Table Nephrops, Irish Sea West (FU15) Commercial fleet tuning series for Northern Ireland and Irish Nephrops trawlers, for males. Effort (first column) is reported as hours ( s) fished, numbers removed are in thousands. Raising procedures documented in the Stock Annex (section B4). Males TUNE DATA :EFFORT 1HRS 12 FLEET Northern Ireland FLEET ROI

18 ICES WGNSDS report Table Nephrops, Irish Sea West (FU15) Commercial fleet tuning series for Northern Ireland and Irish Nephrops trawlers, for females. Effort (first column) is reported as hours ( s) fished, numbers removed are in thousands. Raising procedures documented in the Stock Annex (section B4). Females TUNE DATA :EFFORT 1HRS 12 FLEET Northern Ireland FEMALES TUNE DATA :E FFORT 1H RS 11 IRELAND

19 654 ICES WGNSDS report 25 Landings - International Effort - UK Nephrops trawlers 15 UK - Nephrops directed traw lers 4 Landings (tonnes) International Effort (' hours trawling) LPUE (kg/hour trawling) LPUE UK(NI) - Nephrops directed traw lers UK(E&W) - Nephrops directed traw lers UK - Nephrops directed traw lers Mean size (mm carapace length) Mean sizes - UK Nephrops trawlers Catch Mal < 35 mm CL Catch Fem < 35 Landings Mal < 35 Landings Fem < 35 Landings Mal > 35 Landings Fem > Figure Irish Sea East (FU 14): Long-term trends in landings, effort, CPUEs and/or LPUEs, and mean sizes of Nephrops. 654

20 ICES WGNSDS report Landings Effort Landings (tonnes) Quarterly effort (' hours) Annual effort (' hours) Males Females Total Qtr 1 Qtr 2 Qtr 3 Qtr 4 Total LPUE - Males LPUE - Females 3 3 LPUE (kg/hour trawling) LPUE (kg/hour trawling) Qtr 1 Qtr 2 Qtr 3 Qtr 4 Annual Qtr 1 Qtr 2 Qtr 3 Qtr 4 Annual Figure Irish Sea East (FU 14): Landings, effort and LPUEs by quarter and sex from UK Nephrops directed trawlers. 655

21 656 ICES WGNSDS report 25 LPUE - Males < 35 mm CL LPUE - Females < 35 mm CL 2 2 LPUE (kg/hour trawling) LPUE (kg/hour trawling) Qtr 1 Qtr 2 Qtr 3 Qtr 4 Annual Qtr 1 Qtr 2 Qtr 3 Qtr 4 Annual LPUE - Males > 35 mm CL LPUE - Females > 35 mm CL 2 2 LPUE (kg/hour trawling) LPUE (kg/hour trawling) Qtr 1 Qtr 2 Qtr 3 Qtr 4 Annual Qtr 1 Qtr 2 Qtr 3 Qtr 4 Annual Figure Irish Sea East (FU 14): LPUEs by sex and quarter for selected size groups, UK Nephrops directed trawlers. 656

22 Landings - International ICES WGNSDS report Landings (tonnes) Rep. of Ireland - All gears UK - All gears International Effort (' hours trawling) Effort - Different fleets Rep. of Ireland (no effort data available so far) UK Northern Ireland Nephrops traw lers CPUE and LPUE - Different fleets Mean sizes - Different fleets CPUE or LPUE (kg/hour trawling Rep. of Ireland - LPUE UK Northern Ireland - CPUE UK Northern Ireland - LPUE Mean size (mm carapace length) ROI Catch Males ROI Catch Females UK NI - Catch - Mal UK NI - Catch - Fem Figure Irish Sea West (FU 15): Long-term trends in landings, effort, CPUEs and/or LPUEs, and mean sizes of Nephrops. 657

23 Landings 658 ICES WGNSDS report 25 Effort Landings (tonnes) Quarterly effort (' hours) Annual effort (' hours) Males Females Total Qtr 1 Qtr 2 Qtr 3 Qtr 4 Total CPUE - Males CPUE - Females 4 4 LPUE (kg/hour trawling) LPUE (kg/hour trawling) Qtr 1 Qtr 2 Qtr 3 Qtr 4 Annual Qtr 1 Qtr 2 Qtr 3 Qtr 4 Annual Figure Irish Sea West (FU 15): Landings, effort and CPUEs by quarter and sex from Northern Ireland Nephrops trawlers. 658

24 ICES WGNSDS report CPUE - Males < 35 mm CL CPUE - Females < 35 mm CL 4 4 LPUE (kg/hour trawling) LPUE (kg/hour trawling) Qtr 1 Qtr 2 Qtr 3 Qtr 4 Annual Qtr 1 Qtr 2 Qtr 3 Qtr 4 Annual CPUE - Males > 35 mm CL CPUE - Females > 35 mm CL 1 1 LPUE (kg/hour trawling) LPUE (kg/hour trawling) Qtr 1 Qtr 2 Qtr 3 Qtr 4 Annual Qtr 1 Qtr 2 Qtr 3 Qtr 4 Annual 659

25 66 ICES WGNSDS report 25 Males Females landings Discards 2 landings Discards 25 Numbers 2 15 Numbers Carapace Length Carapace Length Figure Irish Sea East (FU15), Length frequency distributions of male and female landings and discards averaged over

26 ICES WGNSDS report Nephrops Burrow Density no/m2 a Nephrops Burrow Density no/m2 b N N N N N N 54 N 54 N N N N N N N 6 W 5 3W 5 W 6 W 5 3W 5 W Figure Bubble plot of Nephrops burrow densities estimated during the joint Ireland/UK Northern Ireland underwater TV surveys in 23 (a) and 24 (b). + indicates station positions 661

27 662 ICES WGNSDS report 25 Number of stations Density (numbers/m2) Figure 14.9 Frequency distribution of Nephrops burrow density in the Western Irish Sea. 662

28 663 ICES WGNSDS report 25 E5 E4 E3 54.8N N 54.4N N 3 54.N N N N 6.4 W 6.2 W Figure W 5.8 W 5.6 W W 5.2 W 5. W 4.8 W 4.6 W DARD Nephrops Trawl survey stations 663

29 ICES WGNSDS report 25 Mean number of Nephrops >3mm CL vertical bars = SE April females August females April males August males Numbers per nm Figure Mean carapace length of Nephrops from trawl surveys (vertical bars = SE) Mean number of Nephrops <2mm CL vertical bars = SE kg per nm August April number per nm Figure Mean catches from DARD trawl surveys Figure Mean number of <2mm and >3mm CL Nephrops from trawl surveys (vertical bars = SE)