International Council for the Exploration of the Sea
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Workshop on the Inclusion of Discard Survival in Stock Assessments (WKSURVIVE)

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posted on 2023-08-22, 07:12 authored by ICESICES

The introduction of high survivability exemptions from the EU landing obligation has raised questions on how they relate to ICES stock advice and the management of quotas (TACs). Where discard rates are high, and survival rates are limited, substantial quantities of dead discards are generated. On the other hand, high survival rates may result in limited impacts of discarding despite high discard rates. Therefore, to achieve agreed levels of fishing mortality, dead discards should be accounted for in the stock assessment and the advice derived from it. The inclusion of discard survival in stock assessments has wider application also since it can improve estimates of fishing mortality and in turn enhance scientific advice on fishing opportunities.

This ICES workshop, WKSURVIVE, was established to explore and progress the inclusion of discard survival in stock assessments. Participants consisted of researchers with expertise in conducting discard survival experiments and researchers with expertise in stock assessments. The workshop successfully reviewed the approaches taken in existing ICES stocks assessments to integrate discard survival estimates. Three cases were identified: plaice (Pleuronectes platessa) in Division 7.a (Irish Sea), several Norway lobster (Nephrops norvegicus) Functional Units (FUs), and sea bass (Dicentrarchus labrax) in divisions 4.b, 4.c, 7.a, and 7.d–h (although only for recreational catches in this last case). These cases are reviewed and described in the report.

WKSURVIVE identified case study ICES stock assessments for which there is management interest to include discard survival, and for each one mapped to it relevant and robust discard survival evidence. Based on the type of assessment and the associated discard survival evidence, the group agreed on recommendations on the inclusion of discard survival for each stock assessment. A table including the stock assessments, survival evidence, and stock-specific recommendations was a key output from this workshop. The group also reviewed other case studies where the implications of discard survival on stock estimates and reference points are actively being explored, but not yet used in the assessments.

The workshop also included a small seminar with a series of presentations on recent and current research activity related to discard survival. Ten presentations were made and included, among others, the discard survival of Nephrops, sole, rays, and small pelagics. This continues to be an active research area and there is currently substantial attention on the discard survival of rays in particular, which links to the EU conditional survivability exemption for skates and rays and associated evidence roadmap. A summary of each area of research activity is presented here.


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



ICES Scientific Reports





Contributors (Editors)

Thomas Catchpole; Fabian Zimmermann

Contributors (Authors)

Catarina Adão; Amaya Albalat; Loïc Baulier; Katinka Bleeker; Lisa Borges; Michael Breen Massimiliano Cardinale; Thomas Catchpole; Leo Clarke; Tom Clegg; Elsa Cuende; Timothy Earl Clive Fox; Joanna Marie Goley; Ghassen Halouani; Holger Haslob; Kieran Hyder; Junita Diana Karlsen; Dorothée Kopp; Niels Madsen; Marie Morfin; Martin Oliver; Kotaro Ono; Esther Savina Elor Sepp; Bárbara Serra-Pereira; Mickael Teixeira Alves; Maria Tenningen; Sven Sebastian Uhlmann; Julio Valeiras; Noémi Van Bogaert; Paddy Walker; Noëlle Yochum; Fabian Zimmermann



Recommended citation

ICES. 2021. Workshop on the Inclusion of Discard Survival in Stock Assessments (WKSURVIVE). ICES Scientific Reports. 3:41. 59 pp.