Herring (Clupea harengus) in subdivisions 20 24, spring spawners (Skagerrak, Kattegat, and western Baltic)

Transcription

1 ICES Advice on fishing opportunities, catch, and effort Baltic Sea and Greater North Sea Ecoregions Published 31 May Herring (Clupea harengus) in subdivisions 20 24, spring spawners (Skagerrak, Kattegat, and western Baltic) ICES advice on fishing opportunities ICES advises that when the MSY approach is applied, there should be zero catch in This advice applies to the catch of western Baltic spring spawning herring (WBSS) in subdivisions and the eastern part of Subarea 4. Stock development over time The spawning-stock biomass (SSB) has been below Blim since Fishing mortality (F) has been relatively constant slightly above FMSY since Recruitment has been low since the mid-2000s and has been declining in recent years, with the lowest values of the time-series in 2016 and Figure 1 Herring in subdivisions 20 24, spring spawners. Commercial catches, recruitment, fishing mortality, and spawningstock biomass (SSB) from the summary of the stock assessment; 95% confidence intervals are shown for SSB, F, and recruitment. Unshaded value of the recruitment is the geometric mean value of Stock and exploitation status ICES assesses that fishing pressure on the stock is above FMSY and below Fpa and Flim, and spawning-stock size is below MSY Btrigger, Bpa, and Blim. Table 1 Herring in subdivisions 20 24, spring spawners. State of the stock and fishery relative to reference points. ICES Advice

2 Catch scenarios The ICES MSY approach stipulates that F is reduced proportionally to SSB when the spawning stock size falls below MSY Btrigger. When SSB is below Blim, measures should be taken so that SSB can be brought above Blim in the short term. All catch scenarios, including zero catch, result in SSB remaining below Blim in Table 2 Herring in subdivisions 20 24, spring spawners. The basis for the catch scenarios. All weights are in tonnes and recruitment is in thousands. Variable Value Notes F ages 3 6 (2018) 0.30 Catch constraint SSB (2018) Catch constraint R age 0 (2018) Geometric mean R age 0 (2019) Geometric mean Agreed EU Norway catch options (EU Norway, 2016), including an assumed 46% transfer ( t) of the C-fleet TAC to the North Sea (in tonnes). Utilization of the TAC in 2018 of 100% for the F-fleet, 54% for the C-fleet, 46% for the D-fleet, and a small catch of western Baltic springspawning herring in the A-fleet (based on the average of , see table 8 for definition of Total catch (2018) fleets). Ratios between the North Sea and western Baltic herring stocks in Division 3.a and Subarea 4 are based on the average proportions in the catches. ICES Advice

3 Table 3 Herring in subdivisions 20 24, spring spawners. Annual catch scenarios. All weights are in tonnes. Basis Total catch (2019) F 3-6 (2019) SSB* (2019) SSB* (2020) % SSB change ** % advice change *** ICES advice basis MSY approach: zero catch % -100% Other scenarios MAP (2018)^: F = F MSY SSB 2018/MSY B trigger % -22% MAP (2018)^: F = F MSY lower (SSB 2018/MSY B trigger) % -44% MAP (2018)^: F = F MSY upper (SSB 2018/MSY B trigger) % -7.1% F MSY % 7.2% F = F pa % 19.0% F = F lim % 46% SSB (2020) = B lim ^^ % -100% SSB (2020) = B pa^^ % -100% SSB (2020) = MSY B trigger^^ % -100% F = F % 3.6% MAP (2016)^^^: F = F MSY SSB y-1/ MSY MAPB trigger % 5.1% MAP (2016)^^^: F = F MSY.lower SSB y-1/ MSY MAPB trigger % -21% MAP (2016)^^^: F = F MSY.upper SSB y-1/ MSY MAPB trigger % 30% F = 0 {SSB 2021 = } ^^^^ % -100% F = 0.05 {SSB 2021 = } ^^^^ % -81% F = 0.1 {SSB 2021 = } ^^^^ % -63% F = 0.15 {SSB 2021 = } ^^^^ % -46% * For spring-spawning stocks, the SSB is determined at spawning time and is influenced by fisheries and natural mortality between 1 January and spawning time (April). ** SSB (2020) relative to SSB (2019). *** Advised catch 2019 relative to advised catch 2018 ( t) for the western Baltic spring-spawning herring stock. ^ Revised Baltic MAP (2018) which refers to most recent reference points. As SSB is currently (2017) below MSY B trigger, the F lower and F upper values in the MAP are adjusted by the SSB y-1/msy B trigger ratio. ^^ The B lim and B pa cannot be achieved in 2020 even with zero catch advice ^^^ Baltic multiannual management plan (MAP; EU, 2016); MSY MAPB trigger = 110 kt, F MSY.MAP = 0.32, F MSY.MAP lower = 0.23, F MSY.MAP upper = This is not applicable to SD ^^^^ To explore potential development of the stock, projections until 2021 with different low F scenarios are provided, where F 2020 = F There has been a change in perception of the status of the stock after the benchmark in 2018 mainly due to a revision of Blim (ICES, 2018a): The stock is now considered to be below Blim. Recent recruitment has been declining and recruitment in 2016 and 2017 have been the weakest in the time-series. There are no catch scenarios that will rebuild the stock above Blim by ICES advises zero catch under such circumstances. Basis of the advice Table 4 Herring in subdivisions 20 24, spring spawners. The basis of the advice. Advice basis MSY approach An EU Baltic Sea Multiannual Plan (MAP; EU, 2016) was established in 2016 and applies to herring in subdivisions 22 24, which is part of the distribution area of the WBSS stock. The MAP is in the process of Management plan being updated (EC, 2018), the main change is the reference to latest reference points rather than to a fixed list. This plan is not adopted by Norway and, thus, not used as basis of the advice for this shared stock. ICES Advice

4 Quality of the assessment This stock was benchmarked in 2018 (ICES, 2018a). The new assessment shows a better retrospective pattern. The new multi-fleet model adopted at the benchmark is expected to provide a better representation of the temporal development of fishing mortality. New survey indices were added giving a better coverage of younger age-classes of the stock. The historic perception of SSB and recruitment have been revised downwards in this process. Figure 2 Herring in subdivisions 20 24, spring spawners. Historical assessment results; orange lines represent the most recent assessment following the benchmark in The herring assessed in subdivisions is a complex mixture of populations predominantly spawning in spring, but with local components spawning also in autumn and winter. The population dynamics and the relative contribution of these components is presently unknown but are likely to affect the precision of the assessment. Moreover, mixing between WBSS and central Baltic herring in subdivisions may contribute to uncertainty in the assessment. There is interannual variability in the herring migration patterns and in the distribution of the fisheries (including the optional transfer of quotas between divisions 3.a and 4). Since these cannot be predicted, recent average proportions between stocks are assumed in projections. This is an added source of uncertainty in the catch forecasts. Issues relevant for advice The updated biomass reference points (Blim from to tonnes, MSY Btrigger from to tonnes, ICES, 2018a) and the continued decline in recruitment have changed the perception of the stock dynamics. Now SSB has been below Blim since The basis for changing the reference points is the extension of the time-series where consistently low recruitment at low SSB is observed since 2006 (Figure 3). The reductions in catches over the past years, in line with the scientific advice, have not resulted in the anticipated increase in SSB due to weak recruitment. ICES therefore recommends the implementation of measures to facilitate the recovery of the stock in the short term. To explore the potential development of the stock, projections until 2021 with different low F scenarios (where F2020 = F2019) are provided in Table 3. Spawning-tock biomass is expected to remain just below Blim with a fishing mortality of zero. The highest fishing mortality that brings SSB above Blim in 2021 will be F = 0.1 with a yield of tonnes in This will carry a higher risk of not achieving Blim than zero catch in 2019 and ICES Advice

5 Figure 3 Herring in subdivisions 20 24, spring spawners. Stock-recruit-relationship Vertical dashed lines represent B lim ( tonnes) and B pa ( tonnes). The agreed TAC-setting procedure for herring in Division 3.a calculates the TAC for the combined stocks in the C-fleet as 41% of the ICES MSY advice for WBSS plus 5.7% of the TAC advice for the A-fleet. Further, a + /- 15% constraint on the interannual TAC variability applies. However, given the new perception of the stock, which has been below Blim for ten years, there are serious concerns about the status of the WBSS stock. According to the safety clause which is part of the TAC-setting procedure, the procedure itself therefore should not be applied and should be re-evaluated. The ICES advice for zero catch also implies that the TAC for Division 3.a should be set to zero in This impacts on catches of North Sea autumn spawning herring (NSAS) by the C and D fleet in Division 3.a. Western Baltic Spring Spawning (WBSS) herring are also caught as a bycatch of in the fishery targeting NSAS in the eastern part of Division 4.a. The catch of WBSS in the North Sea was around 632 t in Without additional area restriction on the herring fishery in the North Sea in 2019, the catch of WBSS in the North Sea will likely be of a similar magnitude in Under the EU landing obligation, which entered into force in 2015, up to 9% interspecies quota transfers are allowed for stocks that are considered to be within safe biological limits (see Article 15 of EU, 2013). Quota transfers were not considered in this catch advice. The catch of herring under other species quotas (e.g. sprat) under this regulation may result in a substantial risk of overexploitation of WBSS herring. To achieve rebuilding of this stock, any transfer under this regulation should be accounted for in setting the TAC. ICES Advice

6 Reference points Table 5 Framework MSY approach Precautionary approach Management plan (2016) Management plan (2018) Herring in subdivisions 20 24, spring spawners. Reference points, values, and their technical basis. Weights in tonnes. Reference point Value Technical basis Source MSY B trigger B pa equal to the upper 95% confidence limit of B lim. Stochastic simulations (Eqsim) with Beverton-Holt, Ricker, F MSY 0.31 and segmented regression stock recruitment curve from the full time-series ( ). B lim Chosen as the mean of the two lowest SSB (1998, 1999) values with above average recruitment. B pa Upper 95% confidence limit of B lim with σ 0.136, using the CV from the final-year SSB estimate in the assessment. F P50% leading to 50% probability of SSB>Blim under stochastic F lim 0.45 simulations with Beverton-Holt, Ricker, and segmented stock recruitment from the full time-series ( ). F pa 0.35 F pa = F lim exp( σ) with σ 0.145, based on the CV from the terminal assessment year. MAP (2016) EU (2016) Annex II, MSY B trigger as determined in 2013 MSY B trigger column A MAP (2016) B lim B lim as determined in 2013 EU (2016) Annex II, column B MAP (2016) EU (2016) Annex I, 0.32 F MSY as determined in 2013 F MSY columns A and B MAP (2016) Consistent with the ranges provided by ICES (2015), resulting ICES (2015) and target range in no more than a 5% reduction in long-term yield compared EU (2016) Annex I, with MSY. column A F lower MAP (2016) target range F upper MAP (2018) MSY B trigger MAP (2018) B lim MAP (2018) F MSY MAP (2018) target range F lower MAP (2018) target range F upper Consistent with the ranges provided by ICES (2015), resulting in no more than a 5% reduction in long-term yield compared with MSY. ICES (2015) and EU (2016) Annex I, column B B pa equal to the upper 95% confidence limit of B lim Chosen as the mean of the two lowest SSB (1998, 1999) values with above average recruitment. Stochastic simulations (Eqsim) with Beverton-Holt, Ricker, and segmented regression stock recruitment curve from the full time-series ( ). Consistent with the ranges, resulting in no more than 5% reduction in long-term yield compared with MSY. Consistent with the ranges, resulting in no more than 5% reduction in long-term yield compared with MS. Basis of the assessment Table 6 Herring in subdivisions 20 24, spring spawners. Basis of assessment and advice. ICES stock data category 1 (ICES, 2016) Assessment type Age-based analytical assessment, multi-fleet SAM (ICES, 2018a, b) that uses catches by fleet in the model and in the forecast. Two acoustic, two trawl, and one larval survey indices (HERAS, GerAS (BIAS), IBTS Q1, IBTS Q3, and N20); Input data catch statistics and corrections for historical area misreporting; otolith microstructure and morphometric methods to calculate the proportion of NSAS in the catches. Discards and bycatch Discarding is considered to be negligible. The amount of slippage in Division 3.a is unknown. Indicators None. Other information Last benchmarked in 2018 (ICES, 2018a). Working group Herring Assessment Working Group for the Area South of 62 N (HAWG) ICES Advice

7 Information from stakeholders The 46% TAC transfer from Division 3.a to the North Sea in 2018, assumed for the human consumption fishery on herring in the catch forecast, was based on information provided by the Pelagic Advisory Council (AC). History of the advice, catch, and management Table 7 Herring in subdivisions 20 24, spring spawners. ICES advice, TACs, and ICES estimated catch. All weights are in tonnes. Year ICES advice Predicted ICES estimated catch ^ Agreed TAC Agreed TAC catch Division subdivisions Subdiv. 22 corresp. to Division 3.a Subarea 4 Total 3.a*** advice 1987 Reduction in F No increase in F TAC TAC TAC TAC Increased yield from 1993 reduction in F; reduction in juvenile catches TAC If required, TAC not exceeding If required, TAC not exceeding a: managed together with autumn spawners 22 24: if required, TAC not exceeding Should be managed in accordance with NSAS 3.a: managed together with autumn spawners 22 24: if required, TAC not exceeding 3.a: managed together with autumn spawners 22 24: if required, TAC not exceeding 3.a: managed together with autumn spawners 22 24: if required, TAC not exceeding 3.a: managed together with autumn spawners 22 24: if required, TAC not exceeding * ~60000 for SDs ~50000 for SDs ~50000 for SDs Reduce F < regime. Reduce F < regime. Status quo F regime. Status quo F regime. Status quo F ICES Advice

8 Year ICES advice regime. Reduce F 20% towards F 0.1 regime. Reduce F to F = 0.25 regime. Reduce F to F = 0.25 MSY transition in 1 5 years and no increase in catches of WBSS herring in the North Sea F MSY = 0.25 and no increase in catches of WBSS herring in the North Sea F MSY = 0.25 and no optional transfer of catch options to the North Sea Predicted catch corresp. to advice Agreed TAC Division 3.a*** Agreed TAC subdivisions Subdiv ICES estimated catch ^ Division 3.a Subarea 4 Total < < < < Transition to MSY approach < MSY approach (F MSY = 0.28)** < MSY approach (F MSY = 0.32) < MSY approach (F MSY = 0.32) < MSY approach (F = 0.295) < MSY approach 0 * Catch in subdivisions ** Advice for 2015 was for wanted catch. *** Including mixed clupeoid TAC and a bycatch ceiling in the small-meshed fisheries until 2005, and for For 2006, and from 2008, human consumption only, not including industrial bycatch or mixed clupeoids, but including North Sea autumn-spawner catch in fleet C, with an optional 50% transfer from Division 3.a to Subarea 4 since ^ WBSS only. ICES Advice

9 History of the catch and landings Table 8 Herring in subdivisions 20 24, spring spawners. Catch distribution, by stock and by fleet, of WBSS and NSAS herring in 2017 as estimated by ICES. See the advice for North Sea autumn spawners (Table 17 in ICES, 2017) for a historical presentation of this information. Area where WBSS are caught Fleet Fisheries WBSS 2017 NSAS 2017 catch (t) catch (t) Division 3.a C Directed herring fisheries with purse-seiners and trawlers D Bycatches of herring caught in the small-meshed fisheries Subdivisions F All herring fisheries in subdivisions Subarea 4 A Directed herring fisheries with purse-seiners and trawlers Total area C,D,F,A All Table 9 Herring in subdivisions 20 24, spring spawners. Catch distribution of WBSS in 2017 as estimated by ICES. Total catch (2017) Landings Discards tonnes 99.6% directed fishery 0.4% bycatch* tonnes Negligible * Sprat fishery closed early in 2017 by agreement with fishers due to whiting by-catch in the sprat fishery. ICES Advice

10 Table 10 Herring in subdivisions 20 24, spring spawners. History of commercial catch as estimated by ICES, by area and country for all herring stocks caught within the management area for subdivisions Values prior to 2002 are rounded. Weights are in tonnes. Year Skagerrak Denmark Norway Sweden Total Kattegat Denmark Sweden Total Subdivisions Denmark Germany Poland Sweden Total Subdivision 23 Denmark Sweden Total Grand total Year ** * Skagerrak Denmark Faroe Islands Netherlands Germany Lithuania Norway Sweden Total Kattegat Denmark Sweden Germany Total Subdivisions Denmark Germany Poland Sweden Total Subdivision 23 Denmark *** Sweden Total Grand total * Preliminary data. ** 2000 t of Danish catches are missing (ICES, 2007). *** 3103 t officially reported catches (ICES, 2011). ICES Advice

11 Summary of the assessment Table 11 Herring in subdivisions 20 24, spring spawners. Assessment summary. Weights are in tonnes. High and low refer to the 95% confidence intervals. Recruitment F SSB* Catches Year Age 0 High Low High Low Ages 3-6 High Low thousands tonnes tonnes Per year ** *** * SSB measured at spawning time (April). ** Recruitment is the geometric mean of *** SSB is predicted. Sources and references EC European Commission Proposal for a REGULATION OF THE EUROPEAN PARLIAMENT AND OF THE COUNCIL establishing a multiannual plan for fish stocks in the Western Waters and adjacent waters, and for fisheries exploiting those stocks, amending Regulation (EU) 2016/1139 establishing a multiannual plan for the Baltic Sea, and repealing Regulations (EC) No 811/2004, (EC) No 2166/2005, (EC) No 388/2006, (EC) 509/2007 and (EC) 1300/2008. COM (2018) 149 final, 2018/0074 (COD). Brussels, EU Regulation (EU) No 1380/2013 of the European Parliament and of the Council of 11 December 2013 on the Common Fisheries Policy, amending Council Regulations (EC) No 1954/2003 and (EC) No 1224/2009 and repealing Council Regulations (EC) No 2371/2002 and (EC) No 639/2004 and Council Decision 2004/585/EC. EU Regulation (EU) 2016/1139 of the European Parliament and of the Council of 6 July 2016 establishing a multiannual plan for the stocks of cod, herring and sprat in the Baltic Sea and the fisheries exploiting those stocks, amending Council Regulation (EC) No 2187/2005 and repealing Council Regulation (EC) No 1098/2007. Official Journal of the European Union, L 191/1. ICES Advice

12 EU Norway Agreed record of fisheries consultations between Norway and the European Union on the Regulation of Fisheries in Skagerrak and Kattegat for Bergen, 2 December Accessed 8 May 2017 at ICES Report of the Herring Assessment Working Group for the Area South of 62 N (HAWG), March 2007, ICES Headquarters, Copenhagen, Denmark. ICES CM 2007/ACFM: pp. ICES Report of the Herring Assessment Working Group for the Area South of 62 N (HAWG), March 2011, ICES Headquarters, Copenhagen, Denmark. ICES CM 2011/ACOM: pp. ICES EU request to ICES to provide FMSY ranges for selected North Sea and Baltic Sea stocks. In Report of the ICES Advisory Committee, ICES Advice 2015, Book 6, Section S_and_BS_stocks.pdf. ICES Advice basis. In Report of the ICES Advisory Committee, ICES Advice 2016, Book 1, Section 1.2. ICES Herring (Clupea harengus) in Subarea 4 and divisions 3.a and 7.d, autumn spawners (North Sea, Skagerrak and Kattegat, eastern English Channel). In Report of the ICES Advisory Committee, ICES Advice 2017, her.27.3a47d. ICES. 2018a. Report of the Benchmark Workshop on Pelagic Stocks (WKPELA 2018), February 2018, ICES HQ, Copenhagen, Denmark. ICES CM 2018/ACOM: pp. ICES. 2018b. Herring in Division 3.a and subdivisions 22 24, spring spawners. Section 3 in Report of the Herring Assessment Working Group for the Area South of 62 N (HAWG), January 2018 and March 2018, ICES Headquarters, Copenhagen, Denmark. ICES CM 2017/ACOM:07. Available from the ICES library here. ICES Advice