Report of the Herring Assessment Working Group for the Area South of 62°N (HAWG)

Abstract

The ICES herring assessment working group (HAWG) met for seven days in March 2018 to assess the state of five herring stocks and four sprat stocks. HAWG also provided advice for seven sandeel stocks but reported on those prior to this meeting. The working group conducted update assessments for five of the herring stocks. An analytical assessment was performed for North Sea sprat, and data limited assessments (ICES category 3 and 5) were conducted for English Channel sprat and Division 3.a sprat. The assessment of sprat in the Celtic Sea (spr.27.67a–cf–k) was not updated this year. The North Sea autumn spawning herring (her.27.3a47d) SSB in 2017 was estimated at 1.9 mill tonnes while F2–6 in 2017 was estimated at 0.21, which is below the management plan target F2–6 and below FMSY. Fishing mortality on juveniles, mean F0–1 is 0.032, below the agreed ceiling. Recruitment in 2017 is estimated to be very low. The estimate of 0-wr fish in 2017 (2016 year class) is estimated to be at approximately 18 billion, which is very low even compared to other recent low recruitments. Year classes since 2002 are estimated to be consistently weak with year classes 2015 to 2017 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 in 2017 was relatively stable compared to recent years and is estimated to be around 104 000 tonnes. Fishing mortality has been estimated at 0.33 which is is above the estimate of FMSY (0.31). Recruitment has been low since 2006 and 2017 is the lowest observed in the time-series. Under a historical perspective the estimate of SSB of 104 170 tonnes in 2017 is considered low, below both Bpa and Blim, The stock has decreased consistently during the second half of the 2000s and given the continued low recruitments the stock seems not to be able to recover to these higher biomass levels. The Celtic Sea autumn and winter spawning stock (her.27.irls) is estimated to be at a low level, declining from a recent high biomass that peaked in 2011. SSB is currently estimated at 36 000 tonnes in 2017, coming down from 136 000 tonnes in 2011. Mean F(2–5 rings) was estimated at 0.4 in 2017, having increased from 0.06 in 2009. Recruitment has been good in recent years with several strong cohorts (2004, 2008, 2009, 2010 and 2013) entering the fishery but has come down substantially in the most recent years with the poorest year class in 2015. The 2017 SSB estimate of 6.a/7.b, c herring (Her.27.6a7bc) the combined stock of 6.aN and 6.aS/7.b, c was 113 000 tonnes, well below Bpa. Continued low recruitment has caused a decline of the stock which is expected to continue in the near future although fishing mortality is low at 0.05–0.1 in recent years. Irish Sea autumn spawning herring (her.27.nirs) assessment shows a stable SSB in 2017 compared to previous years at around 27 000 tonnes. The stock has experienced large incoming year classes in most recent years. Fishing mortality is estimated at the lowest level in the time series at 0.15, below FMSY. Catches have been relatively stable since the 1980s, and close to TAC levels in recent years. North Sea sprat (spr.27.4) is an ICES category 1 stock with a fully accepted analytical assessment. The stock is estimated to be at the highest level since the 1970s in 2018, driven by relatively high recruitment in 2017. The stock appears to be well above Bpa (142 000 tonnes) in 2018 at 408 808 tonnes. Fishing mortality in the last years has fluctuated between 0.4–2.3. A recent management strategy evaluation (WKMSYREF2) suggested that the Bescapement management strategy is not precautionary. Sprat in Division 3.a (spr.27.3a) was benchmarked in 2013 (WKSPRAT), however, it is an ICES category 3 stock that uses three survey series, from which an abundance index is derived, and landings data. ). The surveys show variability over time without a clear trend. The most recent annual change is positive compared to the 4 years before. Catch advice for sprat in the English Channel (7.d, e) (spr.27.7de) was based on criteria for an ICES category 3-based method. Data available are landings and a short time series of acoustic biomass (2013–2017). The acoustic biomass indicates an overall decline in the stock size. Quantitative advice was provided for Sprat in the Celtic Sea (spr.27.67a–cf–k) in 2017 using an ICES category 5-based method where only data on landings are available; this assessment was not updated this year as the advice is still valid and the perception of the stock has not changed. A sprat benchmark is taking place in the summer/autumn of 2018. The HAWG reviewed the assessments performed on seven sandeel stocks and the related advice of these stocks. Section 11 of this report contains the assessments of sandeel in Division 3.a and Subarea 4.  Standard issues such as the quality and availability of data, estimating the amounts of discarded fish, availability of data through industry surveys and scientific advances relevant for small pelagic fish were discussed.  All data and scripts used to perform the assessment and perform the forecast calculations are available on GitHub and accessible to anyone.