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

Type Article
Date 2019
Language English
Author(s) ICES
Contributor(s) Vermard YouenORCID, Girardin Raphael
Source ICES Scientific Reports/Rapports scientifiques du CIEM (2618-1371) (ICES), 2019 , Vol. 1 , N. 7 , P. 1271p.
DOI 10.17895/

The main terms of reference for the 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 bench-marks 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 and Inter-benchmarks in 2018/2019

No full benchmarks were conducted during 2019 for WGNSSK stocks. However, there were sev-eral inter-benchmark protocol (IBP) meetings during 2018/2019. These were on North Sea turbot and saithe, and on sole in 7.d.

State of the Stocks

The main impression in recent years is that fishing mortality 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 4, 7.d and 20, and only the SSBs of cod in 4, 7.d and 20 and whiting in 4 and 7.d are below MSY Btrigger at the beginning of 2019. Several North Sea stocks are exploited at or below FMSY levels (saithe in 3.a, 4 and 6, plaice in 4 and 20, plaice in 7.d, sole in 7.d, and turbot in 4); however, just as many are being fished above FMSY (cod in 4, 7.d and 20, haddock in 4, 6.a and 20, whiting in 4 and 7.d, sole in 4, and witch in 3.a, 4 and 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 in 2019 (the strongest since the 1999 year-class; to be confirmed with future data).

All Nephrops stocks with agreed biomass reference points (Category 1 stocks, excluding nep.fu.3-4) are currently above MSY Btrigger, and all Nephrops stocks with defined FMSY (Category 1 stocks, including nep.fu.3-4) are being fished at or below FMSY in 2018, apart from Nephrops in FU 6 (nep.fu.6).

WGNSSK is also responsible for the assessment of several data-limited species (Category 3+ stocks) that are mainly by catch in demersal fisheries (brill in 3.a, 4 and 7.d-e, lemon sole in 3.a, 4 and 7.d, dab in 3.a and 4, flounder in 3.a and 4, turbot in 3.a, whiting in 3a), along with striped red mullet in 3.a, 4 and 7.d. Biennial precautionary approach (PA) advice was provided in 2015 for the first time, and again in 2017; for 2019, biennial advice was either PA, where catch advice was still needed, or simply reporting stock status where no catch advice was needed. Reopening of advice was triggered for several Category 1 stocks in the autumn, following the availability of Q3 survey results in 2019, namely cod in 4, 7.d and 20, haddock in 4, 6.a and 20, plaice in 4 and 20, sole in 4, and Nephrops in FU 6, 7 and 8 (Annex 7).

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