Working Group on the Assessment of Demersal Stocks in the North Sea and Skagerrak (WGNSSK)

Section 18 was added in September 2022; In December 2022, Executive summary, Section 11 and Annex 5, 6 and 9 were updated whilst Sections 10 and 12 were added.

The main terms of reference for the ICES Working Group for the Assessment of Demersal Stocks in the North Sea and Skagerrak (WGNSSK) were: to update, quality check and report relevant data for the working group, to update and audit the assessment and forecasts of the stocks, to produce a first draft of the advice on the fish stocks and to prepare planning for benchmarks in future years. Ecosystem changes have been analytically considered in the assessments for cod, haddock and whiting in the form of varying natural mortalities estimated by the ICES Working Group on Multi Species Assessment Methods (WGSAM).

Benchmarks in 2021/2022

Full benchmarks were conducted during 2022 for WGNSSK stocks. These were on haddock in Subarea 4, Division 6.a and Subdivision 20 and plaice in Subarea 4 and Subdivision 20. An inter-benchmark protocol (IBP) meeting took place in summer 2022 for sole in Division 7.d, to include adjustments of the assessment model configuration and tuning indices. 

State of the Stocks

The main impression in recent years is that fishing pressure has been reduced substantially for many North Sea stocks of roundfish and flatfish compared to the beginning of the century. All fish stocks with agreed reference points (Category 1 stocks) are above Blim, apart from cod in Subarea 4, Division 7.d and Subdivision 20. The SSBs of cod in Subarea 4, Division 7.d and Subdivision 20, sole in Subarea 4, sole in Division 7.d, and saithe in Division 3.a, Subareas 4 and 6 are below MSY Btrigger at the beginning of 2022. Also, the SSB of witch in Division 3.a, Subarea 4, Division 7.d, estimated in the middle of the year (at spawning time) 2022 is below MSY Btrigger. Several North Sea stocks are exploited at or below FMSY levels (cod in Subarea 4, Division 7.d and Subdivision 20, haddock in Subarea 4, Division 6.a and Subdivision 20, plaice in Subarea 4 and Subdivision 20, sole in Division 7.d, turbot in Subarea 4, whiting in Subarea 4 and Division 7.d); however, several others are being fished above FMSY (saithe in Division 3.a, sole in Subarea 4, Subareas 4 and 6, plaice in Division 7.d, witch in Division 3.a, Subarea 4, Division 7.d). An important feature is that recruitment still remains poor compared to historic average levels for most gadoids, although there are signs of a strong recruitment for haddock and whiting in 2019 and 2020. Recruitment in 2021 continues on a high level for flatfish stocks of witch in Division 3.a, Subarea 4 and 7d and for plaice in Subarea 4 and Subdivision 20.

All Nephrops stocks with agreed biomass reference points (Category 1 stocks, excluding nep.fu.3-4) are currently above MSY Btrigger, apart from Nephrops in FU 6 (nep.fu.6). All Nephrops stocks with defined FMSY (Category 1 stocks) are being fished below FMSY in 2021, apart from Nephrops in FU 6 (nep.fu.6).

WGNSSK is also responsible for the assessment of several data-limited species (Category 2+ stocks) that are mainly by-catch in demersal fisheries (brill in Division 3.a, Subarea 4 and Division 7.d-e, lemon sole in Division 3.a, Subarea 4 and Division 7.d, dab in Division 3.a and Subarea 4, flounder in Division 3.a and Subarea 4, turbot in Division 3.a, whiting in Division 3.a), along with grey gurnard in Division 3.a, Subarea 4 and Division 7.d and striped red mullet in Division 3.a, Subarea 4 and Division 7.d. Annual advice is required for brill in Division 3.a, Subarea 4 and Division 7.d-e, turbot in Division 3.a as well as lemon sole in Division 3.a, Subarea 4 and Division 7.d. Biennial precautionary approach (PA) advice for striped red mullet in Division 3.a, Subarea 4 and Division 7.d and flounder in Division 3.a and Subarea 4 was provided in 2015 for the first time, and again in 2017, 2019 and 2021. Biennial advice is required on a different cycle for grey gurnard in Division 3.a, Subarea 4 and Division 7.d as well as whiting in Division 3.a, and was provided in 2022. Triennial advice is now required for dab in Division 3.a and Subarea 4 (due in 2022) and pollack in Division 3.a and Subarea 4 (due in 2024).

Biennial PA advice was provided for data-limited Nephrops stocks (Category 4: 10, 32, 33, 34) for the first time in 2016, subsequently in 2018, 2020 and 2022. Since 2022, advice for Nephrops in FU 5 was provided as a category 5 stock (after being downgraded from category 4). For Nephrops in 4 outside functional units biennial PA advice was produced for the first time in 2015; however, it did not make sense to have biennial advice for this unit (Category 5) misaligned with biennial advice for other data-limited Nephrops stocks (Category 4), so in order to achieve alignment, triennial PA advice was provided in 2017, with biennial PA advice given in 2020 in 2022 (aligned with other data-limited Nephrops stocks).