Herring Assessment Working Group for the area south of 62° N (HAWG)

The ICES herring assessment working group (HAWG) met online for four days in May 2022 to assess the state of six herring stocks. Advice for two sprat stocks that have an advice schedule from 1st July–30th June was prepared in April. HAWG also provided advice for eight sandeel stocks in February. The working group conducted update category 1 assessments for four of the herring stocks and category 3 assessments for 2 herring stocks. An analytical assessment was per-formed for the combined North Sea and Division 3.a sprat, and data limited assessment (ICES category 3) was conducted for English Channel sprat (spr.27.7de). Biennial advice is given for sprat in the Celtic Seas and West of Scotland with advice provided in 2021.
The North Sea autumn spawning herring (her.27.3a47d). SSB in 2021 was estimated at 1.35 mill tonnes while F2–6 in 2021 was estimated at 0.20, which is below FMSY. Recruitment in 2021 is the lowest since 2017 and within the low recruitment regime observed since 2015. Year classes since 2002 are estimated to be consistently weak with year classes 2014 and 2016 some of the weakest on record. ICES considers that the stock is still in a low productivity phase.
The Western Baltic spring-spawning herring (her.27.20-24) assessment was updated. The SSB and recruitment in 2021 are at low levels. SSB is estimated to be around 62 800 tonnes which is below both Bpa and Blim. Recruitment has been low since 2006 and it has been further deteriorating with time. Fishing mortality decreased in 2018 and is now well below FMSY (0.31) at 0.15. The stock has decreased consistently during the second half of the 2000s and given the continued low recruitments, the stock is not able to recover above Blim unless a drastic reduction in fishing effort is applied for several years.
The Celtic Sea autumn and winter spawning stock (her.27.irls) is estimated to be at a very low level. SSB is currently estimated to be increasing from the lowest level in the time-series and has been below Blim (34 000 t) since 2016. Mean F(2–5 rings) was estimated at 0.069 in 2021, having de-creased from the peak of 1.2 in 2018. Recruitment has been consistently below average since 2013.
Irish Sea autumn spawning herring (her.27.nirs) assessment shows an increase in SSB in 2021 to 30 792 tonnes which is the highest in the current time series. The stock has experienced large incoming year classes in recent years. Fishing mortality (F4–6) has been stable between 0.2 and 0.21 since 2009 and is below FMSY (0.266).
6aN autumn spawning herring (her.27.6aN) were part of a combined assessment with herring in 6.a South and 7.b-c since 2015. Following a benchmark meeting in 2022, these two stocks are now assessed separately. This was made possible by the development of a genetically split acous-tic survey index. The Malin Shelf herring estimate of SSB for autumn spawning herring in 6.aN in 2021 is 43 886 tonnes. Although estimates have increased from the minimum value in 2019, it should be noted that numbers of herring to the West of Scotland are low compared to historical estimates. Indicators show that fishing pressure on the stock is at or below FMSY proxy (0.335) and the stock size index is above MSY Btrigger proxy (14 711 t).
Herring in 6.aS/7.b, c (her.27.6aS7bc) are now assessed separately from autumn spawn-ing herring in 6aN, following a benchmark in 2022. This was made possible by the devel-opment of a genetically split acoustic survey index. The survey index for herring in 6aS, 7b,c has been increasing since the lowest point in 2016 (36,707 t) and in 2021 was estimated to be 189,856 t, which is the second highest point in the current time series. Recent catches are among the lowest in the time series. Fishing pressure on the stock is at or below FMSY proxy (0.034) and the stock size index is well above MSY Btrigger proxy (51 390 t).
North Sea and 3.a sprat (spr.27.3a4) were combined into a single assessment unit during the 2018 benchmark. Perception of the status of the stock is dominated by the dynamics in Subarea 4 where most of the catches occur. Fishing mortality in the last years has fluctuated at high levels between 0.6–2.2. Low recruitment the last two years have contributed to a decrease in SSB well below MSY Bescapement. The estimates for 2022 show an SSB of 100 000 t which is below Bpa (125 000 t).
Catch advice for sprat in the English Channel (7.d, e) (spr.27.7de) was based on criteria for ICES category 3 stocks using the acoustic survey. The stock went through an interbenchmark in 2021 and a new basis for advice was recommended. The catch advice is now based on the latest biomass index multiplied by a constant harvest rate of 8.57%. Since sprat is a short-lived species and given the timing of the survey in October, an advice period, valid from 1st July to 30st June in the following year, has been adopted for this stock starting in 2022.
Catch advice for sprat in the Celtic Seas and West of Scotland (spr.27.67a-cf-k) was given for 2022 and 2023 using the ICES category 5 based method where only landings data are available. The precautionary buffer was applied and a 20% decrease in catch is advised.
The HAWG reviewed the category 1 assessments performed on four sandeel stocks (SA 1r-3r, 4) and the category 3-6 assessments of four more sandeel stocks (SA 5r, 6, 7r, Div. 6a) and updated the related advice. Section 9 of this report contains the assessments of sandeel in Division 3.a and Subarea 4.
Standard issues such as benchmark planning, the quality and availability of data, availability of data through industry surveys and scientific advances particularly with respect to the use of genetics for stock discrimination were discussed.
All data and scripts used to perform the assessments and the forecast calculations are available at https://github.com/ICES-dk/wg_HAWG and accessible to anyone.


59.104314N, 43.479167S, 16.66406E, -30.796877W

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ICES (2022). Herring Assessment Working Group for the area south of 62° N (HAWG). ICES Scientific Reports/Rapports scientifiques du CIEM. 4 (16). 745pp.. https://doi.org/10.17895/ices.pub.10072, https://archimer.ifremer.fr/doc/00877/98908/

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