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Working Group on Elasmobranch Fishes (WGEF)

Version 2 2022-05-24, 08:45
Version 1 2022-01-18, 14:57
report
posted on 2022-05-24, 08:45 authored by ICESICES

ICES WGEF meets annually and is responsible for providing assessments and advice on the state of the stocks of sharks, skates, and rays throughout the ICES area. In 2021, WGEF provided advice for 16 stocks of rays and skates distributed the North Sea ecoregion, the Azores and MAR; catsharks (Scyliorhinidae) in the Greater North Sea, Celtic Seas and Bay of Biscay and Iberian Coast ecoregions; smooth-hounds in the Northeast Atlantic; and tope shark in the Northeast Atlantic.

Despite improvements of reported landings in the past decade, quality check and error corrections, reliable time-series of landings do not span more than 10–12 years for most stocks. Estimated discards are uncertain because elasmobranchs are mostly bycatch in all types of fisheries and national sampling effort might be insufficient for estimating precise and unbiased discards for elasmobranchs. Further, survival of discarded elasmobranchs is thought to be high but quantitative estimates are scarce so that the relationship between discards and dead catches is unknown. As a consequence, for numerous stocks it is not possible to provide catch advice. For those stocks, advice on landings is formulated. 

The majority of WGEF stocks are assessed as Category 3 stocks, i.e. the advice is based on trends derived from scientific surveys. In November 2020, a workshop (WKSKATE) was held to evaluate criteria for the representativeness of surveys as well as to standardize and revise methods for calculating stock size indicators. Recommendations from WKSKATE were reviewed by the group and applied to the assessments where deemed appropriate. Consequently, for three stocks i.e. thornback ray and lesser spotted dogfish in the greater North Sea (rjc.27.3a47d and syc.27.3a47d) and smooth-hound in the ICES area (sdv.27.nea) surveys were added to the assessment, while for spotted ray in the North Sea (rjm.27.3a47d) the UK(E&W)–BTS–Q3 was excluded. For those stocks classified as ICES category 5 and 6 stocks, i.e. for which even survey data are lacking and only (minor) landings or some bycatch data are available, potential surveys were evaluated. 

No assessment was done for three (tope, gag.27.nea, Rajidae in the greater North Sea, raj.27.3a47d, and blonde ray in Subarea 6 and Division 4a, rjh.27.4a6) out of 16 stocks. For these stocks, advices are only based on landings or catches according to the ICES precautionary approach. In addition, for the three stocks in the Bay of Biscay and Iberian coast ecoregion (two stocks of lesser spotted dogfish, syc.27.8c9a and syc.27.8abd, and one stock of blackmouth dogfish, sho.27.89a) no advice was requested. In the North Sea, among the five stocks for which the trend in biomass could be estimated, this trend was increasing for two stocks (rjc.27.3a47d and spotted ray in divisions 4.c and 7.d, rjh.27.4c7d), decreasing for two (rjm.27.3a47d and cuckoo ray, rjn.27.3a4) and stable for one (lesser spotted dogfish, syc.27.3a47d). In the Celtic Sea, among the three stocks for which the trend in biomass could be estimated, this trend was slightly increasing for two stocks of dogfishes (syc.27.67a-ce-j and syt.27.67) and decreasing for the third one (sho.27.67). Furthermore, for smooth-hound (Mustelus spp.) in the ICES area (sdv.27.nea) an increasing trend in biomass was observed. 

COVID-19 or legal and technical issues caused several surveys not or only partially completed in 2020. For surveys missing 2020 data, the 2 over 5 index ratio was calculated by treating the 2020 value as missing, i.e. the last 2-year average is based on a single value of 2019. If only a part of the 2020 data was missing (e.g. FR-CGFS-Q4) the effect of the lack of survey stations on the biomass indicators was estimated. For stocks where the impact or the missing strata was large or could not be assessed the 2020, data were excluded from the biomass index. 

In March 2022, a benchmark for porbeagle, thornback ray in the Bay of Biscay, cuckoo ray in subareas 6 and 7, and in divisions 8.a–b and 8.d and undulate ray in the English Channel is organised (WKELASMO). Furthermore, a benchmark for three North Sea stocks is proposed for 2023. It will be the first time these stocks will go through a benchmark. In addition, a second WKSKATE workshop that would examine the remaining skate and ray stocks is being planned.

History

Published under the auspices of the following ICES Steering Group or Committee

  • FRSG

Published under the auspices of the following ICES Expert Group or Strategic Initiative

WGEF

Series

ICES Scientific Reports

Volume

3

Issue

59

Contributors (Editors)

Jurgen Batsleer; Pascal Lorance

Contributors (Authors)

Ole Thomas Albert; Thomas Barreau; Jurgen Batsleer; Loïc Baulier; Gérard Biais; Katinka Bleeker; Josá A. A. De Olivera; Guzmán Diez; Jim Ellis; Klara Jakobsdottir; Graham Johnston; Armelle Jung; Claudia Junge; Laura Lemey; Wendel Lleal; Pascal Lorance; Tanja Miethe; Teresa Moura; Mário Rui Pinho; Cristina Rodríguez-Cabello; Régis Santos; Matthias Schaber; Bárbara Serra-Pereira; Joana Silva; Katherine Sosebee; Klaas Sys; Sebastian Uhlmann

ISSN

2618-1371

Recommended citation

ICES. 2021. Working Group on Elasmobranch Fishes (WGEF). ICES Scientific Reports. 3:59. 822 pp. https://doi.org/10.17895/ices.pub.8199