ICES A
DVISORYC
OMMITTEEICES CM 2011/ACOM:05
Report of the Arctic Fisheries Working Group (AFWG)
28 April - 4 May 2011
Hamburg, Germany
International Council for the Exploration of the Sea Conseil International pour l’Exploration de la Mer
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Denmark
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Recommended format for purposes of citation:
ICES. 2011. Report of the Arctic Fisheries Working Group (AFWG), 28 April - 4 May 2011, Hamburg, Germany. ICES CM 2011/ACOM:05. 659 pp.
For permission to reproduce material from this publication, please apply to the Gen- eral 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.
© 2011 International Council for the Exploration of the Sea
Contents
Executive Summary ... 1
0 Introduction ... 4
0.1 Participants ... 4
0.2 Locations of the meeting ... 4
0.3 Terms of reference ... 4
Generic ToRs for Regional and Species Working Groups ... 6
0.4 Unreported landings ... 7
0.5 Uncertainties in the data ... 8
0.6 Climate included in advice of NEA cod ... 16
0.7 Proposals for status of assessments in 2012-2013 ... 16
0.8 ICES Quality Handbook ... 16
0.9 InterCatch ... 16
0.10 MSY-related reference points and advice ... 16
0.11 Answer to request from Norway on monitoring of migratory patterns of fish stocks in the Arctic ... 17
0.12 Recommendations ... 17
0.13 Time and place of Next Meeting ... 17
1 Ecosystem considerations (Figures 1.1-1.19, Tables 1.1-1.17) ... 18
1.1 General description of the Barents Sea ecosystem (Figure 1.1-1.2, Tables 1.1-1.7) ... 18
1.1.1 Geographical description ... 18
1.1.2 Climate ... 19
1.1.3 Bacteria and phytoplankton ... 19
1.1.4 Zooplankton ... 20
1.1.5 Benthos and shellfish ... 20
1.1.6 Fish ... 21
1.1.7 Mammals... 24
1.1.8 Seabirds ... 24
1.1.9 Parasitic organisms ... 25
1.1.10Rare and threatened species ... 25
1.1.11Invasive species ... 25
1.1.12Human activity... 25
1.2 State and expected situation of the ecosystem (Figures 1.3-1.9, Tables 1.3-1.7, 1.9) ... 26
1.2.1 Climate ... 26
1.2.2 Phytoplankton ... 28
1.2.3 Zooplankton ... 29
1.2.4 Northern shrimp ... 29
1.2.5 Fish ... 29
1.2.6 Marine mammals ... 31
Harp Seal ... 31
1.2.7 Future long-term trends ... 31
1.3 Description of the Barents Sea fisheries and its effect on the ecosystem (Tables 1.10-1.11, Figures 1.12-1.18) ... 32
1.3.1 General description of the fisheries ... 33
1.3.2 Mixed fisheries ... 34
1.3.3 Fleet composition ... 35
1.3.4 Impact of fisheries on the ecosystem ... 35
1.4 Ecosystem based management issues and potential assessment improvements (Tables 1.12-1.15) ... 37
1.4.1 Multispecies and ecosystem models ... 37
1.4.2 Operational use of ecosystem information in stock state assessments and prognosis ... 40
1.4.3 Fishery induced evolution ... 44
1.5 Monitoring of the ecosystem (Figure 1.19, Tables 1.16-1.17) ... 46
1.5.1 Standard sections and fixed stations ... 46
1.5.2 Area coverage ... 46
1.5.3 Other information sources ... 48
1.5.4 Spatial data in the Barents Sea ... 48
1.6 Main conclusions ... 49
1.7 Response to “Generic Terms of Reference” and review group ... 50
1.7.1 Concerning Generic Terms of Reference for Regional and Species Working Groups ... 50
1.7.2 Concerning Review Group comments ... 52
2 Cod in subareas I and II (Norwegian coastal waters) ... 83
2.1 Fisheries ... 83
2.1.1 Sampling fisheries and estimating catches (Tables 2.1-2.4, Figures 2.1-2.5) ... 83
2.1.2 Regulations ... 84
2.2 Survey data ... 85
2.2.1 Indices of abundance and biomass (Tables 2.5-2.11, Figures 2.7-2.12)... 86
2.2.2 Age reading and stock separation (Tables 2.4, 2.5, 2.8-2.12) ... 86
2.2.3 Weights at age (Table 2.8) ... 86
2.2.4 Maturity-at-age (Table 2.10, Figure 2.13) ... 86
2.3 Data available for the Assessment ... 87
2.3.1 Catch at age (Table 2.1 and table 2.14) ... 87
2.3.2 Weights at age (Tables 2.8 and 2.13) ... 87
2.3.3 Natural mortality ... 87
2.3.4 Maturity-at-age (Tables 2.10, 2.13, Figure 2.13) ... 88
2.4 Methods used for assessing trends in stock size and mortality (Table 2.13-2.18, Figure 2.16-2.18) ... 88
2.5 Results of the Assessment ... 88
2.5.1 Comparing trends with last year’s assessment (Table 2.6,
2.15-2.18, Figures 2.6, 2.13-2.14, 2.16-2.18) ... 88
2.5.2 Recruitment (Table 2.6, Figure 2.16) ... 89
2.5.3 Catches in 2011 ... 89
2.6 Comments to the Assessment ... 89
2.7 Reference points ... 90
2.8 Management considerations ... 90
2.9 Rebuilding plan for coastal cod ... 90
2.10 Recent ICES advice ... 91
2.11 Response to the comments from the review group ... 91
3 North-East Arctic Cod (Subareas I and II) ... 129
3.1 Status of the fisheries ... 129
3.1.1 Historical development of the fisheries (Table 3.1a) ... 129
3.1.2 Reported catches prior to 2011 (Tables 3.1-3.3, Figure 3.1) ... 129
3.1.3 Unreported catches of Northeast Arctic cod in 2002-2010 ... 129
3.1.4 TACs and advised catches for 2010 and 2011 ... 130
3.2 Status of research ... 130
3.2.1 Fishing effort and CPUE (Table A1) ... 130
3.2.2 Survey results - abundance and size at age (Tables 3.4, A2- A14) ... 130
3.2.3 Age reading ... 132
3.3 Data used in the assessment ... 132
3.3.1 Catch at age (Tables 3.5-3.6) ... 132
3.3.2 Weight at age (Tables 3.7 and 3.8-3.9, A2, A4, A6, A8, A12). ... 132
3.3.3 Natural mortality ... 133
3.3.4 Maturity at age (Tables 3.10 and 3.11)... 133
3.3.5 Cannibalism (Table 3.12) ... 133
3.4 Assessment using VPA model (Tables 3.13, A13) ... 134
3.4.1 XSA settings (Figure 3.2a, Table 3.13a) ... 134
3.4.2 Including cannibalism in XSA (Tables 3.7, 3.12) ... 135
3.4.3 XSA tuning diagnostics (Table 3.14-3.15, Figure 3.2b-3.4) ... 136
3.4.4 Results (Table 3.16-3.26, Figure 3.1) ... 136
3.5 Results of the assessment ... 137
3.5.1 Fishing mortalities and VPA ... 137
3.5.2 Recruitment (Table 1.13) ... 137
3.6 Reference points and harvest control rules ... 137
3.6.1 Biomass reference points (Figure 3.1) ... 137
3.6.2 Fishing mortality reference points ... 137
3.6.3 Harvest control rule ... 137
3.6.4 Target reference points ... 138
3.7 Prediction ... 139
3.7.1 Prediction input (Tables 3.22, 3.27, Figure 3.5a-b, 3.6, 3.7) ... 139
3.7.2 Prediction results (Tables 3.28, 3.29a-b) ... 140
3.8 Comparison with last year’s assessment ... 140
3.9 Additional assessment methods ... 141
3.9.1 Survey calibration method (Figures 3.8-3.9) ... 141
3.9.2 Gadget (Figure 3.10) ... 141
3.10 Comments to the assessment ... 141
3.11 New data sources ... 142
3.11.1Catch data (Tables 3.30, 3.31, 3.1b) ... 142
3.11.2Consumption data ... 142
3.11.3Survey data (Table A14) ... 142
3.12 Answering to last year comments from Reviewers: ... 143
4 Northeast Arctic Haddock (Subareas I and II) ... 223
4.1 Status of the Fisheries ... 223
4.1.1 Historical development of the fisheries ... 223
4.1.2 Landings prior to 2011 (Tables 4.1–4.3, Figure 4.1A) ... 223
4.1.3 Catch advice and landings for 2010 and 2011 ... 223
4.2 Status of Research ... 224
4.2.1 Survey results (Tables B1-B4, 4.9-4.11) ... 224
4.2.2 Weight-at-age (Tables B5, B6) ... 225
4.3 Data Used in the Assessment ... 225
4.3.1 Estimates of unreported catches (Tables 4.1-4.3) ... 225
4.3.2 Catch-at-age (Table 4.4) ... 225
4.3.3 Weight-at-age (Tables 4.5–4.6, Table B.6) ... 225
4.3.4 Natural mortality (Table 4.7) ... 225
4.3.5 Maturity-at-age (Table 4.8) ... 226
4.3.6 Changes in data from last year (Tables 4.1-4.3) ... 226
4.4 Assessment Using VPA ... 226
The assessment method was also this year XSA. ... 226
4.4.1 Data for tuning (Table 4.9) ... 226
4.4.2 VPA and tuning (Table 4.9) ... 226
4.4.3 Recruitment indices (Table 4.10, Table 4.11, Figure 4.1C) ... 228
4.4.4 Prediction data (Table 4.11, Table 4.19) ... 228
4.5 Results of the Assessments ... 229
4.5.1 Comparison of assessments ... 229
4.5.2 Fishing mortality and VPA (Tables 4.12–4.18 and Figures 4.1A-D, 4.5-4.6) ... 229
4.5.3 Catch options for 2012 (Tables 4.19 - 4.22) ... 230
4.6 Comments to the assessment and forecasts ... 230
4.7 Reference points and harvest control rules (Tables 4.23 and Figures 4.2-4.3) ... 231
4.7.1 Biomass reference points ... 231
4.7.2 Fishing mortality reference points ... 232
4.7.3 Harvest control rule ... 232
4.8 Comments to Technical Minutes from reviewers ... 233
5 Saithe in Subareas I and II (Northeast Arctic)... 293
5.1 The Fishery (Tables 5.1.1-5.1.2, Figure 5.1.1) ... 293
5.1.1 ICES advice applicable to 2010 and 2011 ... 293
5.1.2 Management applicable in 2010 and 2011 ... 294
5.1.3 The fishery in 2010 and expected landings in 2011 ... 294
5.2 Commercial catch-effort data and research vessel surveys ... 294
5.2.1 Fishing Effort and Catch-per-unit-effort (Table 5.2.1) ... 294
5.2.2 Survey results (Table 5.2.2, Figure 5.2.1) ... 295
5.2.3 Recruitment indices ... 295
5.3 Data used in the Assessment... 295
5.3.1 Catch numbers at age (Tables 5.3.1-5.3.2) ... 295
5.3.2 Weight at age (Table 5.3.3) ... 296
5.3.3 Natural mortality ... 296
5.3.4 Maturity at age (Table 5.3.4) ... 296
5.3.5 Tuning data (Table 5.3.5, Figure 5.3.1) ... 296
5.4 Exploratory runs (Table 5.4.1, Figure 5.4.1) ... 297
5.5 Final assessment run (Tables 5.5.1-5.5.7, Figures 5.5.1-5.5.4) ... 297
5.5.1 Fishing mortalities and VPA (Tables 5.5.2-5.5.7, 5.7.1, Figure 5.5.5) ... 297
5.5.2 Recruitment (Table 5.3.2, Figure 5.1.1) ... 298
5.6 Reference points (Figure 5.6.1) ... 298
5.6.1 Biomass reference points ... 299
5.6.2 Fishing mortality reference points (Tables 5.6.1, 5.7.1, Figure 5.1.1) ... 299
5.6.3 Harvest control rule (Figures 5.6.2-3) ... 299
5.7 Predictions ... 300
5.7.1 Input data (Table 5.7.1) ... 300
5.7.2 Catch options for 2012 (short-term predictions) (Tables 5.7.2-5.7.4) ... 300
5.7.3 Comparison of the present and last year’s assessment... 300
5.8 Comments to the assessment and the forecast (Figure 5.5.5). ... 301
5.9 Response to ACOM technical minutes ... 301
6 Beaked redfish (Sebastes mentella) in Subareas I and II ... 350
6.1 Status of the Fisheries ... 350
6.1.1 Development of the fishery ... 350
6.1.2 Bycatch in other fisheries ... 350
6.1.3 Landings prior to 2011 (Tables 6.1–6.5, D1-D2, Figure 6.2) ... 350
6.1.4 Expected landings in 2011 ... 351
6.2 Data used in the Assessment... 351
6.2.1 Length- composition from the fishery (Figures 6.3-6.4) ... 351
6.2.2 Catch at age (Tables 6.6 and 6.8, Figure 6.14 and D4) ... 352
6.2.3 Weight at age (Tables 6.7 and 6.9) ... 352
6.2.4 Maturity at age (Tables D8a,b) ... 352
6.2.5 Scientific surveys (Figures D1 and D2) ... 352
6.3 Results of the Assessment ... 356
6.4 Comments to the assessment ... 357
6.5 Biological reference points... 358
6.6 Management advice ... 358
6.7 Implementing the ICES Fmsy framework ... 359
6.8 New approaches to modeling population dynamics of redfish ... 360
6.9 Response to RGAFNW Technical minutes ... 361
7 Golden redfish (Sebastes marinus) in Subareas I and II ... 402
7.1 Status of the Fisheries ... 402
7.1.1 Recent regulations of the fishery ... 402
7.1.2 Landings prior to 2011 (Tables 7.1–7.4, D1 & D2, Figures 7.1-7.2)... 402
7.1.3 Expected landings in 2011 ... 403
7.2 Data Used in the Assessment (Figure E1) ... 403
7.2.1 Catch-per-unit-effort (Table E1, Figure 7.3) ... 403
7.2.2 Catch at length and age (Table 7.5) ... 404
7.2.3 Weight at Age (Table 7.6)... 404
7.2.4 Maturity at age (Figure 7.7) ... 404
7.2.5 Survey results (Tables E2a,b-E3a,b-E4, Figures 7.4a,b– 7.5a,b) ... 404
7.3 Assessment with the GADGET model ... 404
7.3.1 Description of the model... 404
7.3.2 Data used for tuning ... 404
7.3.3 Changes made to the model and in input data compared with last year’s Working Group ... 404
7.3.4 Assessment results using the Gadget model... 404
7.4 State of the stock ... 404
7.5 Comments on the Assessment ... 404
7.6 Biological reference points... 404
7.7 Management advice ... 404
7.8 Implementing the ICES Fmsy framework ... 404
7.9 Response to RGAFNW Technical Minutes ... 404
8 Greenland halibut in subareas I and II ... 439
8.1 Status of the fisheries ... 439
8.1.1 Landings prior to 2011 (Tables 8.1 - 8.5, F10) ... 439
8.1.2 ICES advice applicable to 2010 and 2011 ... 439
8.1.3 Management applicable in 2010 and 2011 ... 440
8.1.4 Expected landings in 2011 ... 441
8.2 Status of research ... 441
8.2.1 Survey results (Tables 1.1, F1-F8) ... 441
8.2.2 Commercial catch-per-unit-effort (Table 8.6 and F9) ... 443
8.2.3 Age readings ... 443
8.3 Data used in the assessment ... 444
8.3.1 Catch-at-age (Table 8.7) ... 444
8.3.2 Weight-at-age (Table 8.8) ... 444
8.3.3 Natural mortality ... 444
8.3.4 Maturity-at-age (Tables 8.9) ... 444
8.3.5 Tuning data ... 445
8.4 Recruitment indices (Tables A14, F1-F9) ... 445
8.5 Methods used in the assessment ... 445
8.5.1 VPA and tuning (Figure 8.1, Tables 8.7-8.10) ... 445
8.6 Results of the Assessment ... 445
8.6.1 Results of the VPA (Figure 8.2, Tables 8.11-8.15) ... 446
8.6.2 Biological reference points ... 446
8.6.3 Catch options for 2012 ... 446
8.7 Comparison of this year’s assessment with last year’s assessment ... 446
8.8 Comments to the assessment (Figures 8.3 – 8.7) ... 447
8.9 Further work on assessment methods ... 448
8.10 Response to ACOM technical minutes ... 449
9 Barents Sea Capelin ... 500
9.1 Regulation of the Barents Sea Capelin Fishery ... 500
9.2 Catch Statistics (Table 9.1, 9.2) ... 500
9.3 Sampling ... 500
9.4 Stock Size Estimates ... 501
9.4.1 Acoustic stock size estimates in 2010 (Table 9.3) ... 501
9.4.2 Recruitment estimation in 2010 (Table 9.4) ... 501
9.5 Other surveys and information from 2011 ... 501
9.6 Stock assessment ... 502
9.7 Reference points ... 503
9.8 Regulation of the fishery for 2011 ... 503
9.9 The Barents Sea capelin benchmark assessment 2009 ... 503
10 Working documents ... 514
11 References ... 516
Annex 1 - List of Participants ... 528
Annex 2 – Stock Annex Cod Coastal ... 530
Annex 3 - Quality Handbook ANNEX:_NEA Cod ... 537
Annex 4 - Quality Handbook ANNEX:NEA Haddock ... 550
Annex 5 – Stock Annex Northeast Arctic Saithe ... 562
Annex 6: Quality Handbook ANNEX:_Smentella ... 582
Annex 7 Quality Handbook ANNEX:afwg-smr ... 592 Annex 8 Quality Handbook ANNEX:_afwg-ghl-arct ... 598 Annex 9: Barents Sea capelin Stock ... 608
Annex 10 : Stock Data Problems Relevant to Data Collection –AFWGError! Bookmark not defined.
Annex 11 - Technical Minutes of the Arctic and North-Western Review Group (RGANW) 2011 ... Error! Bookmark not defined.
Executive Summary
Cod in subareas I and II (Norwegian coastal waters)
The cod in subareas I and II, Norwegian coastal waters was assessed on the basis of a survey time series 1995-2010 as well as catch at age data (including recreational and tourist fisheries).
• The stock has varied without a clear trend since 2002. Both the stock biomass and the recruitment are at a low level compared to the first years in the time series.
• A rebuilding plan for this stock has now been approved by ICES and adopted by Norwegian authorities.
Cod in Sub-areas I and II (Northeast Arctic) was assessed using XSA. The age range for stock size dependent catchability was extended from 3-5 to 3-6 as this gave a bet- ter fit to the data.
• The fishing mortality (F5-10) has declined since 2005 and is esti- mated to 0.27 for 2009 and 0.29 for 2010. In the time series from 1946 to present, such low values have only been calculated for 1990 and 1946. Estimated SSB for 2010 is 1,134,000 t, which is the highest since 1947. Compared to last years’ assessment, this as- sessment represents a 1% downward revision of the 2010 SSB and a 4% downward revision of F in 2009. Unchanged XSA settings would have given a higher present stock size.
• The new “hybrid” recruitment model, introduced in 2008, was used, resulting in recruitment at age 3 of 433 million in 2011, 607 million in 2012 and 683 million in 2013.
• A catch in 2012 corresponding to the amended HCR is 751,000 t.
This catch corresponds to a fishing mortality of 0.35 in 2012. SSB is estimated to increase from 1,311,000 t at the beginning of 2011 to 1,551,000 t in 2012. These values are the highest in the time se- ries. Earlier maturation means that a larger proportion of the total stock is spawners now compared to the late 1940s when SSB also was calculated to be above 1,000,000 t.
Haddock in Sub-areas I and II (Northeast Arctic) was assessed using XSA with some changes in the settings from last year based on discussions at the 2011 bench- mark meeting (WKBENCH) and at the AFWG meeting.
• Previously (1950-2000) the fluctuation in the haddock stock has shown a strong cyclic pattern caused by occasionally strong re- cruitment, where the stock biomass has been dominated by single cohorts. This picture has changed in recent years where three subsequent cohorts (2004-2006) all are very abundant.
• The fishing mortality (F4-7) in the last three years has declined somewhat and is in 2010 estimated to 0.25. The current assess- ment estimated the total stock to be about 13 % higher and SSB 23
% higher in 2010 compared to the previous assessment. F in 2009 is very close to the estimate from last year.
• In the projection RCT3 was used to estimate recruiting year classes from 2008 and onwards. The results indicate that all the
year classes 2008-2010 are intermediate, with the 2009 year class being the strongest of those three.
• The evaluated and agreed HCR gives a catch in 2012 of 317,000 t, corresponding to F=0.35. The only year with a higher catch than this was 1973. The SSB is expected to reach a peak and all-time high in 2012 (414,000 tonnes) and then decline, while the total stock biomass already has started to decrease from the 2010 peak.
The 2010 total stock biomass of 1.3 million is the highest observed in the time series, which goes back to 1950.
• Flim and Fpa were revised because of revision of the time series.
The new values of Flim=0.77 and Fpa=0.47 are higher than the pre- vious values (0.49 and 0.35, respectively). In the current HCR management is based on Fpa. However, FMSY is now estimated at 0.35, and it seems very appropriate to continue using the HCR with value of target F=0.35. This will correspond to the goal of the management strategy for this stock and will provide maximum sustainable yield.
The assessment of haddock is uncertain, and XSA is sensitive to settings which can give different perception of the long time trend in stock dynamics. However, the short time trends seem to be captured and agree well with results from surveys. Dif- ficulties in estimating initial stock size are additional problems in the forecast.
Saithe in Sub-areas I and II (Northeast Arctic) was assessed using XSA with the same settings as last year. These are based on the analysis done at WKROUND in February 2010.
• In the projections the geometric mean age 3 recruitment of 168 million was used for the 2008 and subsequent year classes.
• A catch in 2012 corresponding to the evaluated and implemented HCR is 164,000 t. This catch corresponds to a fishing mortality of 0.32 in 2012. SSB is estimated to decrease from 358,000 t at the be- ginning of 2011 to 313,000 t in 2012.
Difficulties in estimating initial stock size are the major problem in the forecast. This is due to divergent indices of abundance used in the tuning of the XSA, in addition to lack of reliable recruitment estimates. Prediction of catches beyond the TAC year will, to a large extent, be dependent on assumptions of average recruitment.
In 2011 the evaluation of the harvest control rule made in 2007 was repeated taking into account the changes made to the assessment after the 2010 benchmark assess- ment. The analyses indicate that the HCR still is in agreement with the precautionary approach.
Long-term stochastic simulations made in 2011 showed that the highest long-term yield was obtained for F=0.20, but the curve was almost flat between F=0.15 and F=0.25 and the decrease in long-term yield going from F=0.25 to F=0.35 (Fpa, and also the value used in the present harvest control rule) was rather small (about 5%). How- ever, SSB was reduced by almost 50% between F=0.20 and F=0.35 and approached Bpa.
Beaked redfish (Sebastes mentella) in Sub-areas I and II (Northeast Arctic) was as- sessed on the basis of available trends in the fisheries and surveys, as there is no ac- cepted analytical assessment for this stock. There are signs of improved recruitment, but the stock is still at a low level and will remain there for a considerable period ir- respective of current management actions. No directed fishery is advised.
Golden redfish (Sebastes marinus) in Sub-areas I and II (Northeast Arctic) was as- sessed on the basis of available trends in the fisheries and surveys. There is no ac- cepted analytical assessment for this stock but the Gadget model was used for the seventh time as an experimental analytical assessment model.
• Since 1993, recruitment of S. marinus has been extremely low
• commercial data and surveys show consistent declining trends in the spawning biomass
• the exploratory assessment conducted using the Gadget simula- tion model covering the period 1986–2010 showed a reduction of the spawning stock to about 50% of the level in the early 1990s, and a more severe reduction of the recruitment and the immature stock
• present available information confirms last year’s evaluation of the very poor status of the stock
• catches have been stable in recent years, and with a declining stock size this indicates that the fishing mortality is increasing
Greenland halibut in Sub-areas I and II (Northeast Arctic) is in the category “same advice as last year” this year and last year’s advice (catches should not exceed 13,000 t) was repeated. Stock trends in recent years indicate a slight increase in stock size.
There is no accepted analytical assessment for the time being. The age reading work- shop held in February 2011 (WKARGH) did not lead to agreement on the age reading methodology. Several new age reading methodologies all indicate considerably slower growth after age 4-5 than the old methodology gives.
According to ToR b), the data on Barents Sea capelin were updated.
Before the next AFWG meeting, there will be a benchmark meeting for all redfish stocks, including the two assessed by AFWG.
0 Introduction 0.1 Participants
Asgeir Aglen Norway
Matthias Bernreuther Germany
Mette Bertelsen (part-time) ICES Bjarte Bogstad (Chair) Norway
Oleg Bulatov Russia
Jose Miguel Casas Spain
Anatoly Chetyrkin Russia
Gjert Endre Dingsør Norway
Konstantin Drevetnyak Russia
Anne Maria Eikeset Norway (by correspondence)
Anatoly Filin Russia
Åge Fotland Norway
Elvar Halldor Hallfredsson Norway
Daniel Howell Norway
Yuri Kovalev Russia
Sigbjørn Mehl Norway
Kjell H. Nedreaas Norway
Alexey Russkikh Russia
Oleg Smirnov Russia
Jan Erik Stiansen Norway
Ross Tallman Canada
Oleg Titov Russia
Natalia Yaragina Russia
0.2 Locations of the meeting
The meeting was held in Hamburg, Germany, at the Johann Heinrich von Thünen- Institut (vTI), Institute of Sea Fisheries, who provided excellent facilities for the meet- ing. It was noted that the previous time the AFWG met in Hamburg was in 1965.
0.3 Terms of reference
The Arctic Fisheries Working Group [AFWG]: (Chaired by: Bjarte Bogstad, Norway) will meet in Hamburg, Germany 28 April- 4 May 2011 to:
a ) Address generic ToRs for Fish Stock Assessment Working Groups (see ta- ble below).
b ) For Barents Sea capelin oversee the process of providing intersessional as- sessment.
c ) Address request from Norway on monitoring of migratory patterns of fish stocks in the Arctic
The assessments will be carried out on the basis of the stock annex in National Labo- ratories, prior to the meeting. This will be coordinated as indicated in the table below.
Material and data relevant for the meeting must be available to the group no later than 14 days prior to the starting date.
AFWG will report by 11 May 2011 (and 7 October 2011 for Barents Sea capelin) for the attention of ACOM.
Fish
Stock Stock Name Stock
Coord. Assesss.
Coord. 1 Assess.
Coord.2 Perform
assessment Advice cod-
arct Cod in Subareas I and II (Northeast
Arctic) Russia Norway Norway Y Update
cod-
coas Cod in Subareas I and II (Norwegian
coastal waters) Norway Norway Y Update
had-
arct Haddock in Subareas I and II
(Northeast Arctic) Russia Norway Y Update
sai-
arct Saithe in Subareas I and II
(Northeast Arctic Norway Norway Y Update
cap- bars
Capelin in Subareas I and II (Barents Sea), excluding Division IIa west of
5°W Norway Russia Norway Y Update
ghl-
arct Greenland halibut in Subareas I & II Russia Norway Y
Same advice as last year smn-
arct Red fish Sebastes mentella Subareas I
and II Russia Norway Y Update
smr-
arct Red fish Sebastes marinus Subareas I
and II Norway Russia Y
Same advice as last year ToR a) and b) are addressed in the sections for the respective stocks, while ToR c) is addressed in Section 0.11.
Generic ToRs for Regional and Species Working Groups
The following ToRs apply to: AFWG, HAWG, NWWG, NIPAG, WGWIDE, WGBAST, WGBFAS, WGNSSK, WGCSE, WGDEEP, WGHMM, WGEF and WGANSA.
The working group should focus on:
ToRs a) to g) for stocks that will have advice,
ToRs b) to f) and h) for stocks with same advice as last year.
ToRs b) to c) and f) for stocks with no advice.
a) Produce a first draft of the advice on the fish stocks and fisheries under con- siderations according to ACOM guidelines and implementing recommenda- tions from WKMSYREF.
b) Update, quality check and report relevant data for the working group:
i ) Load fisheries data on effort and catches (landings, discards, bycatch, including estimates of misreporting when appropriate) in the IN- TERCATCH database by fisheries/fleets. Data should be provided to the data coordinators at deadlines specified in the ToRs of the indi- vidual groups. Data submitted after the deadlines can be incorporated in the assessments at the discretion of the Expert Group chair;
ii ) Abundance survey results;
iii ) Environmental drivers.
iv ) Propose specific actions to be taken to improve the quality of the data (including improvements in data collection).
c) Produce an overview of the sampling activities on a national basis based on the INTERCATCH database and report the use of InterCatch;
d) In cooperation with the Secretariat, update the description of major regulatory changes (technical measures, TACs, effort control and management plans) and comment on the potential effects of such changes including the effects of newly agreed management and recovery plans.
e) For each stock update the assessment by applying the agreed assessment method (analytical, forecast or trends indicators) as described in the stock an- nex. If no stock annex is available this should be prepared prior to the meet- ing.
f) Produce a brief report of the work carried out by the Working Group. This re- port should summarise for the stocks and fisheries where the item is relevant:
i ) Input data (including information from the fishing industry and NGO that is pertinent to the assessments and projections);
ii ) Where misreporting of catches is significant, provide qualitative and where possible quantitative information and describe the methods used to obtain the information;
iii ) Stock status and 2012 catch options;
iv ) Historical performance of the assessment and brief description of quality issues with the assessment;
v ) Mixed fisheries overview and considerations;
vi ) Species interaction effects and ecosystem drivers;
vii ) Ecosystem effects of fisheries;
viii ) Effects of regulatory changes on the assessment or projections;
g) Where appropriate, check for the need to reopen the advice in autumn based on the new survey information and the guidelines in AGCREFA (2008 report).
h) For the stocks where the advice is marked 'collate data', available data should be collected and presented as far as possible. If information is available for more than or only part of the area, the header for the stock can be adapted (please discuss with the secretariat).
i) Identify elements of the EGs work that may help determine status for the 11 Descriptors set out in the Commission Decision (available at
http://eurlex.europa.eu/LexUriServ/LexUriServ.do?uri=OJ:L:2010:232:0014:002 4:EN:PDF;
j) Provide views on what good environmental status (GES) might be for those descriptors, including methods that could be used to determine status.
k) take note of and comment on the Report of the Workshop on the Science for area-based management: Coastal and Marine Spatial Planning in Practice (WKCMSP) http://www.ices.dk/reports/SSGHIE/2011/WKCMSP11.pdf l) provide information that could be used in setting pressure indicators that
would complement biodiversity indicators currently being developed by the Strategic Initiative on Biodiversity Advice and Science (SIBAS). Particular consideration should be given to assessing the impacts of very large renewa- ble energy plans with a view to identifying/predicting potentially catastrophic outcomes.
m) identify spatially resolved data, for e.g. spawning grounds, fishery activity, habitats, etc.
The generic terms of reference g-m are answered in Section 1.1 0.4 Unreported landings
In this report, the terms ‘landings’ and ‘catches’ are, somewhat incorrectly, used as synonyms, as discards are in no cases used in the assessments. This does not, how- ever, that discards are negligible for all stocks, but the WG has no information on the possible extent of discarding.
As last year, a report from the Norwegian-Russian analysis group dealing with esti- mation of total catch of cod and haddock in the Barents Sea in 2010 was presented to AFWG (WD09). The report presents estimated catches made by Norwegian, Russian and third countries separately. According to that report the total catches of both cod and haddock reported to AFWG are very close (within 1%) to the estimates made by the analysis group. Thus it was decided to set the IUU catches for 2010 to zero.
It should, however, be noted that there is some disagreement between the Parties in the analysis Group on the interpretation of mandate of the Group and the approach to be used. Mutual inspection of the other Parties’ data, has, for instance, not been carried out. Thus one of the Parties has asked the Joint Norwegian-Russian Fisheries Commission for a clarification of how the mandate should be interpreted.
Unreported landings will reduce the effect of management measures and will un- dermine the intended objectives of the harvest control rule. It is therefore important that management agencies ensure that all catches are counted against the TAC. The AFWG therefore expects that Norway and Russia will continue the work to secure
the necessary quality and accuracy of the catch statistics. Inspections at sea need to be an important part of this work, and Norway and Russia have check-points in their respective economic zones where all fishing vessels have to pass. There are at present, however, no such operative check-points for the fisheries in Spitsbergen waters, and it is suggested by the WG that check-points also should be deployed in this area. The working group also believes that mutual exchange of satellite-tracking (VMS) data from each country’s vessels, also when operating in its own economic zone or in in- ternational waters, may improve the quality of the catch data used for stock assess- ments of joint stocks, and suggests that the Joint Norwegian-Russian Fisheries Commission opens up for that in the future.
0.5 Uncertainties in the data Catch data
At recent AFWG meetings it has been recognized that there is considerable evidence of both substantial mis-/unreporting of catches and discarding throughout the Bar- ents Sea for most groundfish stocks having taken place (ICES CM 2002/ACFM:18, ICES CM 2001/ACFM:02, ICES CM 2001/ACFM:19, Dingsør WD 13 2002 WG, Hareide and Garnes WD 14 2002 WG, Nakken WD 10 2001 WG, Nakken WD8 2000 WG, Schöne WD4 1999 WG, Sokolov, WD 9 2003 WG, Ajiad et al. WD18 2005 WG, WD 24 2004 WG and WD2 2008 WG). In addition to these WDs, Dingsør (2001) esti- mated discards in the commercial trawl fishery for Northeast Arctic cod (Gadus mor- hua L.) and some effects on assessment, and Sokolov (2004) estimated cod discard in the Russian bottom trawl fishery in the Barents Sea in 1983-2002. This work should be continued, updated and presented annually to the AFWG.
During the present AFWG meeting specific concerns were expressed about discard- ing of small haddock on the nursery grounds in the Russian economic zone, and dis- carding of cod related to big catches when the skipper hauls the next trawl before the previous catch is processed. The combination of great amounts and fishable concen- trations of cod and haddock, reduced minimum legal fish size limits in the Norwe- gian Economic zone and in the Svalbard area (Spitsbergen archipelago), may due to large amounts of large and better paid fish and a reduced possibility for the enforce- ment agencies to close small-fish areas (due to more liberal legal catch sizes), lead to a greater risk for discarding. Discarding has the last year again arisen in the Norwegian management and media debate, and quantification of the problem, whether insignifi- cant or not, should be done routinely. The Norwegian Institute of Marine Research has hence designed a project to do this, but has so far not got it financed.
The capelin catch is not considered misreported. Discarding is considered negligible.
Survey data
While the area coverage of the winter surveys for demersal fish was incomplete in 1997 and 1998, the coverage was normal for these surveys in 1999-2002. In the au- tumn 2002, 2006 and winter 2003, 2007 however, surveys were again incomplete due to lack of access to both the Norwegian and Russian Economic Zones. This affects the reliability of some of the most important survey time series for cod and haddock and consequently also the quality of the assessments. In some years, the permission to work in the Norwegian and Russian Economic Zones, respectively, has been received so late that the work has been severely hampered, e.g., the Russian survey in autumn 2003 and 2006. There is no acceptable way around this problem except asking the Norwegian and Russian authorities to give each other's research vessels full access to
the respective economical zones when assessing the joint resources, as, e.g., was the case for Norwegian winter surveys in 2004-2005 and 2008-2011.
From 2004 onwards, a joint Norwegian-Russian survey has been conducted in Au- gust-September. This is a multi-purpose survey termed an “ecosystem survey” be- cause most part of the ecosystem is covered; including an acoustic survey for the pelagic species, which is used for capelin assessment, and a bottom trawl survey which include non-commercial species. Ongoing work is considering the perform- ance of these new index series for inclusion in the assessment of cod and haddock, and they seem to be fairly consistent with the other series available. The ecosystem survey is now included in the haddock assessment. The survey is also utilised in the assessment of redfish and Greenland halibut. However, this survey may be discon- tinued or downscaled for economical reasons. This is highly regrettable, since this survey has been shown to be valuable for sampling of synoptic ecosystem informa- tion, cover the entire area of fish distribution in the Barents Sea, and provide addi- tional data on geographical distribution of demersal fish, which could prove valuable in future inclusion of more ecosystem information in the fish stock assessments.
Age reading
In 1992, PINRO, Murmansk and IMR, Bergen began a routine exchange program of cod otoliths in order to validate age readings and ensure consistency in age interpre- tations (Yaragina et al. 2009b, AFWG 2008, WD 20). Later, a similar exchange program has been established for haddock, capelin, Greenland halibut and S. mentella otoliths.
Once a year (for capelin every second year, no exchanges of redfish age readers so far) the age readers have come together and evaluated discrepancies, which are sel- dom more than 1 year, and the results show an improvement over the time period, despite still observing discrepancies for cod in the magnitude of 15-30%. An observa- tion that is supported by the results of a NEA cod otolith exchange between Norway, Russia and Germany (Høie et al. 2009, AFWG 2009, WD 6). 100 cod otoliths were read by 3 Norwegian, 2 Russian and 1 German reader, reaching nearly 83% agreement (coefficient of variation 8%). The age reading comparisons of these 100 cod otoliths show that there are no reading biases between readers within each country. How- ever, there is a clear trend of bias between the readers from different countries, Rus- sian age readers assign higher ages than the Norwegian and German age readers.
This systematic difference is a source of concern and is also discussed in Yaragina et al. (2009b). This seems to be a persistent trend and will be revealed in the following annual otolith and age reader exchanges.
A positive development is seen for haddock age readings showing that the frequency of a different reading (usually ±1 year) has decreased from above 25% in 1996-1997 to about 10% at present. The discrepancies are always discussed and a final agreement on the exchanged cod and haddock otoliths is at present achieved for all otoliths ex- cept ca. 2-5%. To determine the effects of changes in age reading protocols between contemporary and historical practices, randomly chosen cod otolith material from each decade for the period 1940s-1980s has been re-read by experts (Zuykova et al.
2009). Although some year-specific differences in age determination were seen be- tween historical and contemporary readers, there was no significant effect on length at age for the historical time period. A small systematic bias in the number spawning zones detection was observed, demonstrating that the age at first maturation in the historic material as determined by the contemporary readers is younger than that determined by historical readers. The difference was largest in the first sampled years constituting approximately 0.6 years in 1947 and 1957. Then it decreased with time
and was found to be within the range of 0.0-0.28 years in the 1970-1980s. The study also shows that cod otoliths could be used for age and growth studies even after long storage.
The exchange meeting in 2009 (WD14), found that the percent disagreement between the PINRO and IMR readings have stabilized in recent years at around 20% for cod, and around 10% for haddock, which suggests that annual meetings are not necessary.
For the future meetings will be every second year, while otolith exchange will take place annually.
For capelin otoliths there is a very good correspondence between the Norwegian and Russian age readings, with a discrepancy in less than 5% of the otoliths. An interna- tional (Russia, Norway, Iceland, Canada) age reading workshop on capelin was con- ducted in May 2009 (WD 1). Otoliths from 20 samples (390 otoliths) where discussed.
Some of these samples had been exchanged earlier, according to the program of an- nual otolith exchange between Norway and Russia. Other samples were read for the first time during the workshop, including samples from Iceland and Newfoundland.
For some of the samples, a very high agreement was reached after the initial reading by the different experts. In other cases, some disagreement was evident after the first reading. After the initial reading, the results were analysed. The otoliths that caused disagreement were read again and discussed among the readers. After discussion about the reasons for disagreement, some readers wanted to change their view on some of the otoliths. When the samples were read once more, the agreement was 95
%.
It was concluded that experts from all laboratories normally interpret capelin otoliths equally. Difficult otoliths are sometimes interpreted differently, but these samples are few, and should not cause large problems for common work on capelin biology and stock assessment. All participants noted the great value of conducting joint work on otolith reading, and it was decided to continue the programme of capelin otolith ex- change and to involve the labs at Iceland and Newfoundland in the exchange pro- gram. Readers from Norway and Russia will continue to meet at Workshops every second year. Readers from all labs involved will meet less frequently. Details will be discussed and decided by correspondence.
An ICES Workshop on Greenland halibut age reading (WKARGH) was held in Feb- ruary 2011 (ICES CM 2011/ACOM:41). The results of that workshop are discussed in Chapter 8.
From 2009 onwards, an exchange of Sebastes mentella otoliths is conducted annually between the Norwegian and Russian laboratories (See Section 6.2.2), but it is also im- portant that age readers from the two countries work together.
Sampling error – catch and survey data
Estimates of sampling error are to a large degree lacking or are incomplete for the input data used in the assessment. However, the uncertainty has been estimated for some parts of the input data:
Catch data
For the Norwegian estimates of catch at age for cod and other demersal species methods for estimating the precision have been developed, and the work is still in progress (Aanes and Pennington 2003, Hirst et al. 2004, Hirst et al. 2005). The methods are general and can in principle be used for the total catch, including all countries’
catches, and provide estimates both at age and at length groups. Typical error coeffi- cients of variation are in the range 5-40% depending on age and year. It is evident that the estimates of the oldest fish are the most imprecise due to the low numbers in the catches and resulting small number of samples on these age groups. From 2006 onwards, the Norwegian catch at age in the assessment has been calculated using the method described by Hirst et al. (2005).
Aging error is another source of uncertainty, which causes increased uncertainty in addition to bias in the estimates: An estimated age distribution appears smoother than it would have been in absence of aging error. Some data have been analysed to estimate the precision in aging (Aanes 2002). If the aging error is known, this can cur- rently be taken into account for the estimation of catch at age described above.
For capelin, the uncertainty in the catch data is not evaluated. The catch data are used, however, only when parameters in the predation model are updated at infre- quent intervals, and the uncertainty in the catch data is considered small in compari- son with other types of uncertainties in the estimation.
Survey data
For the Barents Sea winter survey, the sampling error is estimated per length group, but not per age group. Since the ages are sampled stratified per length groups in this survey, it is not straightforward to estimate the sampling error per age group. How- ever, this is possible by for example using similar methods as for the catch data (see Hirst et al. 2004).
The capelin stock is estimated at the August-September survey. After the survey be- came a multipurpose survey in 2004, there is a possibility that the amount of trawl catches directed on capelin acoustic registrations has been less than before, as the to- tal number of trawl stations increased. The effect of this on the quality of the capelin estimate has not been quantified. The survey coverage is considered adequate. The uncertainty in the survey has been evaluated by resampling (Tjelmeland 2002), and used as basis for the CV (0.2) chosen for the survey uncertainty in the tool used for calculating the effect of the catch (CapTool) on the spawning stock.
Work on quantifying uncertainties also for other input data sets should be encour- aged.
Sampling effort - commercial fishery
Concerns about commercial sampling: The main Norwegian sampling program for demersal fish in ICES areas I and II has been port sampling, carried out on board a vessel travelling from port to port for approximately 6 weeks each quarter. A detailed description of this sampling program is given in Hirst et al. (2004). However, this program was, for economic reasons, terminated 1 July 2009. Although sampling by the ‘reference fleet’ and the Coast Guard has increased somewhat in recent years, this change seems to have increased the uncertainty in the catch-at-age estimates (WD6).
For the 2009 data, the effect is strongest for saithe, where the fishery is fairly evenly distributed by quarters. Cod and haddock are mainly fished in the first half of the year, so the effect of the change will for those stocks show up much stronger in the 2010 data. Nevertheless, there are already concerns that the commercial sampling could become so poor that analytical assessments cannot be made in the future. The split between coastal cod and NEA cod will affected by this, but no analysis of this is yet available.
Table 0.1 and Figure 0.1 show one way of presenting the Norwegian commercial catch sampling in 2010 compared with 2009. The main reason for the general decrease in numbers of samples is the termination of the port sampling program in northern Norway. Since this program terminated in the middle of 2009, it would have even been better to compare 2010 with 2008, the last year when all seasons were covered.
The samples and data basis behind each stock assessment are discussed more in de- tail under each stock chapter (e.g., the coastal cod), but some general aspects may be mentioned here. The cod age sampling has been reduced by nearly 50% per 1000 t caught, and haddock and saithe by about 20% dependent on whether the number of samples or the number of aged individuals per 1000 t caught are looked at. The num- ber of aged individuals per 1000 t is now well below the standard set by EU in their Data collection regulations. It is therefore to be expected that the current assessments of these stocks may be less precise than in recent years. In addition to this overall re- duction in sampling which mainly is related to the coastal areas, Figure 0.1-0.2 shows some bias in the sampling coverage of seasons, areas and gears relative to the catch taken. This is elaborated more in detail in each stock chapter.
Stock Year Age samples
Average number per sample
Landings, tonnes
Age samples per 1000 t
Aged individuals per 1000 t
EU DCF for comparison, per 1000 t
NEA-cod 2008 453 62 196067 2.3 144 125
2009 485 58 224816 2.2 125 125
2010 311 50 263816 1.2 59 125
Coastal cod *) 2008 356 11 25777 13.8 152 -
2009 359 7 24821 14.5 101 -
2010 275 8 22925 12.0 96 -
NEA-haddock 2008 212 54 72553 2.9 159 125
2009 263 45 104882 2.5 114 125
2010 275 34 123517 2.2 76 125
NEA-saithe 2008 169 56 165998 1.0 57 125
2009 118 57 144570 0.8 46 125
2010 180 35 173969 1.0 36 125
S. marinus 2008 104 41 6180 16.8 683 125
2009 110 38 6215 17.7 665 125
2010 107 28 6515 16.4 460 125
S. mentella **) 2009 3 40 2567 1.2 46 125
2010 5 64 2245 2.2 143 125
*) in addition to age the otoliths are also used for identification of coastal cod
**) age samples from surveys with commercial trawl come in addition
Table 0.x. Age sampling by Norway of commercial landings in 2008-2010. Number of samples and average number of fish per sample. Also number of age samples and aged individuals per 1000 t caught. For comparison is also the EU DCF requirements shown.
Port sampling along the Norwegian coast should hence be increased. The cut in sam- pling effort of coastal fisheries (composing nearly 70% of the Norwegian cod fisher- ies) is even worse than it looks like from Table 0.1 and Figures 0.1-0.2 since the previous port sampling program managed to sample 200-300 different vessels per year, while the current sampling only manage to cover about 5% of this number.
NEA-cod 2009
NEA-cod 2010
NEA-haddock 2009
NEA-haddock 2010
Figure 0.1. Norwegian AGE samples of commercial catches of NEA-cod and -haddock in 2009 and 2010. Note the different axes and colours. The different sampling platforms are shown by different colours, unfortunately with different colours each year.
NEA-saithe 2009
NEA-saithe 2010
S. marinus 2009
S. marinus 2010
Figure 0.2. Norwegian AGE samples of commercial catches of NEA-saithe and Sebastes marinus in 2009 and 2010. Note the different axes and colours. The different sampling platforms are shown by different colours, unfortunately with different colours each year.
Due to the adopted amendments of the Russian Federal Law "On fisheries and pres- ervation of aquatic biological resources" coming into force, especially concerning the destruction of biological resources caught under scientific research, sampling activi- ties in 2010 (age sample numbers and mass measurements of fish) onboard fishing vessels were reduced, especially in ICES Sub-areas IIа and IIb, which may result in greater uncertainty of the stock assessments due to possible biases in the age-length distributions of the commercial catch.
The methodological ICES workshops WKACCU (ICES CM 2008/ACOM:32), WKPRE- CISE (ICES CM 2009/ACOM:40) and WKMERGE (ICES CM 2010/ACOM:40) were all deal- ing with different aspects of catch sampling and the need for a more proper, robust and transparent sampling design for countries involved in catch sampling. The work- shops have provided valuable general knowledge in how such catch sampling pro- grams can be designed and the reports are beneficial for countries aiming to improve the current situation.
As most stock assessment models used at present in ICES (such as standard VPA and the XSA) work with the assumption that the Catch-At-Age data are unbiased, and know exactly, it seems very important to actually be able to assess if this assumption is reasonable by measuring the accuracy of the estimated catch-at-age based on data from sampling programs. Some of the recommendations from different assessment working groups are further related to assessment of the quality of different estimates such as catch-at–age data. To be able to give validation on the data quality it is crucial that the sampling program is set up in a transparent, statistical sound way. Stock as- sessments need proper sampling designs and estimation processes that are well documented.
ICES’ Planning Group of Commercial Catches, Discards and Biological Sampling (PGCCDBS; ICES CM 2011/ACOM:40) was requested by WGCHAIRS 2011 to de- velop some templates for reporting on quality of input data for stock assessments, e.g., based on the recommendations from the above mentioned ICES workshops. This implies a need for easily comprehended overviews of how data quality has varied over time. A range of such templates would be needed according to the nature of the data (e.g. landings; discards quantities; length or age compositions). Developing time-series of precision and bias values is, however, extremely complex due to the propagation of errors through multi-stage sampling for length/age or discards at the national fleet level and then through the aggregation across fleets and countries.
PGCCDBS has in their report (ICES CM 2011/ACOM:40) suggested that data quality templates for assessment Review Groups should be based around informative sum- maries of sampling coverage and intensity, and should include relative standard er- rors (RSE) or bias estimates only where the standard errors and bias indicators can be reliably estimated and combined across countries and/or fleets. PGCCDBS suggests formats for documenting international sampling coverage and intensity over the full time period of data available for use in stock assessment. Suggested example of a detailed summary of sampling coverage, intensity and bias indicators (WKACCU traffic lights) for a single year is also presented.
And furthermore, a suggested template for how to present the precision (relative standard error) of estimated total international catch-at-age (retained and discarded), and effective sample size is given. Precision of estimated mean length in the catches is also given as an additional indicator.
The AFWG supports the suggestions by PGCCDBS and will now await a decision by ACOM on which templates and parameters that should be estimated and included in future WG reports as standard.
0.6 Climate included in advice of NEA cod
For the fourth time climate information has been applied in the advice from AFWG.
In this year’s assessment ecosystem information was directly used in the projection of NEA cod. A combination of regression models, which is based on both climate and stock parameters, were used for prediction of recruitment at age 3.
In addition, temperature is part of the NEA cod consumption calculations that goes into the historical back-calculations of the amount of cod, haddock and capelin eaten by cod.
0.7 Proposals for status of assessments in 2012-2013
The AFWG propose to set the following status for assessments for each stock:
FishStock Stock Name Advice
in 2012*
Previous
benchmark Next benchmark cod-arct Cod in Subareas I and II (Northeast Arctic) Update - - cod-coas Cod in Subareas I and II (Norwegian coastal waters) Update - - had-arct Haddock in Subareas I and II (Northeast Arctic) Update WKBENCH 2011 -
sai-arct Saithe in Subareas I and II (Northeast Arctic) Update WKROUND 2010 -
cap-bars Capelin in Subareas I and II (Barents Sea),
excluding Division IIa west of 5°W Update WKSHORT
2009 -
ghl-arct Greenland halibut in Sub-areas I & II Update - 2013 smn-arct Redfish Sebastes mentella Subareas I and II Update - 2012 smr-arct Redfish Sebastes marinus Subareas I and II Update - 2012 Any benchmark assessment for Greenland halibut should also include the other stocks of this species in the ICES area and it should also include experts on Greenland halibut stocks outside the ICES area.
0.8 ICES Quality Handbook
Quality Handbooks for all stocks are presented in this report as annexes (no. 2-9). The stock annex for haddock has been updated after the benchmark at WKBENCH 2011, and the stock annex for capelin is new.
0.9 InterCatch
The assessment of NEA cod, haddock and saithe was partly based on output from InterCatch. In the future, AFWG will consider using Intercatch also for the other stocks.
0.10 MSY-related reference points and advice
AFWG has followed the guidelines for MSY-based advice outlined by WKFRAME2 (ICES C. M. 2011/ACOM:33). This year, new analyses of MSY have been made for haddock and saithe, and preliminary MSY analyses for capelin are described in the new stock Annex.
0.11 Answer to request from Norway on monitoring of migratory patterns of fish stocks in the Arctic
ICES has received the following request from the Joint Russian-Norwegian Fisheries Commission (JRNFC) (ToR c)
“According to paragraph 14.1 of the protocol of the 38th session of JRNFC, the parties agreed to “make a request to ICES on continuous monitoring of the extensiveness in the Arctic Ocean of fish stocks managed by the Commission”. The joint management of fish stocks under the JRNFC encompasses the species of Northeast Arctic cod, Northeast Arctic haddock, Barents Sea capelin and Northeast Arctic halibut.
In view of the above described agreement in the protocol of the 38-th session of the JRNFC, the chairmen would hereby request ICES to:
a) Report on the possibility of conducting continuous monitoring of the migra- tory pattern in the Arctic Ocean of fish stocks (referred to above) managed by the JRNFC.
b) Facilitate future monitoring and research of fish stocks in the Arctic Ocean by anchoring the matter in the mandate of an existing ICES Working Group or in the establishment of a new Working Group. “
Our answer is as follows:
We assume that “Northeast Arctic halibut” should be “Northeast Arctic Greenland halibut”.
Concerning a), it is possible to monitor the geographic distribution of these stocks in the ice-free parts of the Arctic Ocean once a year, using existing survey methodology.
The Joint Ecosystem Survey in August/September (Anon. 2010) already covers the Barents Sea north to 80-81°N, and there is also additional Russian coverage of the Greenland halibut distribution in the Northeastern Kara Sea. These surveys could be extended into the Arctic Ocean if possible (depending on ice conditions) and if addi- tional funding is provided.
Concerning b), we advise that future requests to ICES concerning monitoring and research of fish stocks in the part of the Arctic Ocean adjacent to the Barents Sea should be handled by the Arctic Fisheries Working Group, since the stocks handled by AFWG are those that are most likely to migrate into the Arctic Ocean. A new or- ganization might be appropriate if there are fisheries issues that engage more coun- tries around the Arctic Ocean.
0.12 Recommendations
A benchmark meeting for all Greenland halibut stocks should be held in 2013.
Sampling effort and coverage should be improved.
Estimation of international discards in the Arctic fisheries should be conducted and presented to the AFWG annually
0.13 Time and place of Next Meeting
The Working Group proposes to meet next time in Copenhagen (WD 25) in the pe- riod 19-25 April 2012.
1 Ecosystem considerations (Figures 1.1-1.19, Tables 1.1-1.17) The aim of this chapter is to identify important ecosystem information influencing the fish stocks, and further show how this knowledge may be implemented into the fish stock assessment and predictions. There has been steady development in this aspect over the last few years and the work is still in a developing phase. Hopefully, the gathering of information on the ecosystem in this chapter will lead to a better under- standing of the complex dynamics and interactions that takes place in the ecosystem, and also supports the development of an ecosystem based management of the Bar- ents Sea.
At the end of this chapter (Section 1.7) we also answer the ICES “Generic Terms of Reference for Regional and Species Working Groups”.
The ecosystem approach to management is variously defined, but in principle it puts emphasis on a management regime that maintains the health of the ecosystem along- side appropriate use of the marine environment, for the benefit of current and future generations (Jennings, 2004).
Along with fishery, changes in the Barents Sea ecosystem are mainly caused by varia- tions in the ocean climate. A warm period is characterized of increased impact of warm Atlantic water in the Barents Sea contributing to advection of zooplankton, faster growth rate in fish and emergence of abundant year classes (Dalpadado et al.
2002). A cold period is, conversely, characterized by reduced primary biological pro- duction in the Barents Sea and emergence of weak year classes of commercial species.
Climatic conditions govern the formation of primary biological production and feed- ing conditions for fish, as well as the survival of their offspring. In addition, inter- species trophic relations are an important factor that influences the abundance dy- namics of commercial species.
Movement towards an ecosystem approach to the fishery management in the Barents Sea should include (Filin and Røttingen, 2005):
• More extensive use of ecosystem information in the population parameters applied in assessment and prognosis,
• Expansion of the use of multi-species models for fishing management.
This chapter is in general based on the “Joint Norwegian-Russian environmental status 2008, report on the Barents Sea Ecosystem” (Stiansen et al., 2009), affiliating more than 100 scientists from 24 institutions in Norway and Russia. It is further based on Stiansen et al., (WD24), which is an update of the current situation chapter of the Stiansen et al. (2009) report. Additional information is also gathered from other ICES WG’s reports and WD’s to this AFWG assessment. Text, figures and tables taken from these reports (i.e. Stiansen et al., 2009, and Stiansen et al. WD24) are in general not further cited in this chapter.
1.1 General description of the Barents Sea ecosystem (Figure 1.1-1.2, Tables 1.1-1.7)
1.1.1 Geographical description
The Barents Sea is on the continental shelf surrounding the Arctic Ocean. It connects with the Norwegian Sea to the west and the Arctic Ocean to the north and the Kara Sea to the east. Its contours are delineated by the continental slope between Norway
and Spitsbergen to the west, the top of the continental slope towards the Arctic Ocean to the north, Novaya Zemlya archipelago to the east, and the coasts of both Norway and Russia to the south (Figure 1.1). It covers an area of approximately 1.4 million km2, has an average depth of 230 m, and a maximum depth of about 500 m at the western end of Bear Island Trough (Figure 1.1). Its topography is characterized by troughs and basins (300 m – 500 m deep), separated by shallow bank areas, with depths ranging from 100-200 m. The three largest banks are Central Bank, Great Bank and Spitsbergen Bank. Several troughs over 300 m deep run from central Barents Sea to the northern (e.g. Franz Victoria Trough) and western (e.g. Bear Island Trough) continental shelf break. These troughs allow the influx of Atlantic waters to the cen- tral Barents Sea.
1.1.2 Climate
The general pattern of circulation (Figure 1.1) is strongly influenced by the topogra- phy, and is characterised by inflow of relatively warm Atlantic water, and coastal water from the west. This Atlantic water current divides into two branches: 1) a southern branch that flows parallel to the coast and eastwards towards Novaya Zem- lya; and 2) a northern branch that flows into the Hopen Trench. The Coastal Water has more fresh-water runoff and a lower salinity than the Atlantic water; it also has a stronger seasonal temperature signal. In the northern region of the Barents Sea, fresh and cold Arctic waters flow from northeast to southwest. Atlantic and Arctic water masses are separated by the Polar Front, which is characterised by strong gradients in both temperature and salinity. In the east the Polar Front is controlled by topography and quite stationary while it is much weaker and varying in the east. There is large inter-annual variability in ocean climate related to variable strength of the Atlantic water inflow, and exchange of cold Arctic water. Thus, seasonal variations in hydro- graphic conditions can be quite large. Ice cover has a strong seasonal and inter- annual variation, ranging from almost ice free conditions to cover more than half the sea.
1.1.3 Bacteria and phytoplankton
In the biogeochemical cycles of the ocean, a multitude of processes are catalyzed by Bacteria and Archaea, and the functioning of these cycles in the Barents Sea does not differ qualitatively from those at lower latitudes. Both bacteria and viruses show highly variable abundance in the Barents Sea. The situation in the ice-covered areas in the north remains to be investigated.
The Barents Sea is a spring bloom system. During winter, primary production is close to zero. Timing of the phytoplankton bloom varies throughout the Barents Sea and there may also be a high inter-annual variability. The spring bloom starts in the south-western areas and spreads north and east with the retracting ice. In early spring, the water is mixed from surface to bottom. Despite adequate nutrient and light conditions for production, the main bloom does not occur until the water be- comes stratified.
Stratification of water masses in different areas of the Barents Sea may occur in sev- eral ways; 1) through fresh surface water from melting ice along the marginal ice zone; 2) through solar heating of surface layers in Atlantic water masses; or 3) through lateral dispersion of waters in the southern coastal region (Rey, 1981). As in other areas, diatoms are also the dominant phytoplankton groups in the Barents Sea (Rey, 1993). Diatoms particularly dominate the first part of the spring bloom, and the concentration of diatoms can reach up to several million cells per litre. They require
