HERRING ASSESSMENT WORKING GROUP FOR THE AREA SOUTH OF 62° N (HAWG)

Valerio Bartolino, Dorte Bekkevold, Florian Berg, Benoit Berges, Tanja Baagoe Buch, Cindy J. G. van Damme, Mikael van Deurs, Afra Egan, Michael Gras, Thomas Grösler, Ole Henriksen, Kirsten Birch Håkansson, Espen Johnsen, Jan Arge Jacobsen, Matthias Kloppmann, Cecilie Kvamme, Christophe Loots, Mathieu Lundy, Susan Maersk Lusseau, Steven MackinsonHenrik Mosegaard, Richard Nash, Martin Pastoors, Mark Payne, Lisa Readdy, Anna Rindorf, Norbert Rohlf, Claus Reedtz Sparrevohn, Vanessa Trijoulet

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Abstract

The ICES herring assessment working group (HAWG) met for seven days in March 2019 to assess the state of five herring stocks and three sprat stocks. HAWG also provided advice for seven sandeel stocks but reported on those prior to this meeting in February. The working group conducted update assessments for the five herring stocks. An analytical assessment was performed for the combined North Sea and Division 3.a sprat, and data limited assessments (ICES category 3 and 5) were conducted for English Channel sprat (spr.27.7de) and sprat in the Celtic Sea (spr.27.67a–cf–k).

The North Sea autumn spawning herring (her.27.3a47d) SSB in 2018 was estimated at 1.9 mill tonnes while F2–6 in 2018 was estimated at 0.21, which is below FMSY. Fishing mortality on juveniles, mean F0–1 is 0.028, below the agreed ceiling. Recruitment in 2018 has increased compared to 2017 but remains within the low recruitment regime observed since 2015. 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 2018 is estimated to be around 74 132 tonnes. Fishing mortality has been estimated at 0.416 which is above the estimate of FMSY (0.31). Recruitment has been low since 2006 and continues to decrease with 2018 the lowest observed in the time-series. Under a historical perspective the estimate of SSB in 2018 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 is not able to recover above Blim unless a drastic reduction in fishing effort is applied.
The Celtic Sea autumn and winter spawning stock (her.27.irls) is estimated to be at a very low level, declining from a high biomass that peaked in 2011. SSB is currently estimated at 23 000 tonnes in 2018, coming down from 136 000 tonnes in 2011. The stock is now below Blim (34 000 t). Mean F(2–5 rings) was estimated at 0.33 in 2018, having increased from 0.06 in 2009. Recruitment has been consistently below average since 2013.The assessment of the combined stock of herring in 6.aN and 6.aS/7.b, c (Her.27.6a7bc) went through an interbenchmark procedure in 2019 and the advice is now based on trends from an analytical assessment. SSB and recruitment have been declining since around 2000 and are currently at the lowest level in the time series. Fishing mortality has reduced since 2016 when catches have been limited to a scientific monitoring TAC but recovery of the stock is hampered by the very low recruitment.
Irish Sea autumn spawning herring (her.27.nirs) assessment shows a stable SSB in 2018 compared to previous years at around 22 020 tonnes. The stock has experienced large incoming year classes in most recent years. Fishing mortality (F4–6) is estimated at 0.16, one of the lowest in the time series and below FMSY (0.266). Catches have been relatively stable since the 1980s, and close to TAC levels in recent years. North Sea and 3.a Sprat (spr.27.3a4) were combined into a single assessment unit during the recent WKSPRAT benchmark. The long-term dynamics and perception of the status of the combined stock is consistent with previous perception for sprat in Subarea 4. Despite the fact that fishing mortality in the last years has fluctuated at high levels between 0.6–2.2, recruitments slightly above the average during recent years have contributed to an increase in SSB well above MSY Bescapement. The estimates for 2019 show an SSB of 249 000 t which is nearly double of Bpa (125 000 t).
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 (2013–2018). 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) using an ICES category 5-based method where only data on landings are available.
The HAWG reviewed the assessments performed on seven sandeel stocks and the related advice of these stocks. Section 9 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 particularly with respect to stock discrimination relevant for small pelagic fish were discussed. 
All data and scripts used to perform the assessments and perform the forecast calculations are available on GitHub and accessible to anyone.
Original languageEnglish
Place of PublicationCopenhagen
PublisherInternational Council for the Exploration of the Sea (ICES)
Number of pages982
DOIs
Publication statusPublished - 2019
SeriesICES Scientific Report
Number2
Volume1
ISSN2618-1371

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