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Inter-Benchmark Protocol on East and Southwest Greenland Cod 2

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posted on 2021-09-10, 00:00 authored by ICESICES
The Inter-Benchmark Protocol on East and Southwest Greenland Cod 2 (IBPGCOD2) was established as a result of the rejection of the regular assessment in 2021 conducted by the Northwestern Working Group (NWWG) of cod (Gadus morhua) in ICES Subarea 14 and NAFO Division 1.F (East Greenland, Southwest Greenland). This was due to a violation of the predefined limits for retrospective bias. IBPGCOD2 decided to focus on a short-term technical fix to solve the assessment problems, as data for a more systematic solution are not available. The most likely explanation for the difficulties in assessing the stock arises from the mixing of the stock with both the neighbouring Icelandic cod on Dohrn Bank and the West Greenland cod stock, a process which has increased in recent years as indicated by changes in fishing patterns and abundance of older fish. IBPGCOD2 suggests, following an in-depth sensitivity analysis, altering the natural mortality (M) to account for changes in immigration and emigration. M is therefore reduced for age groups 5+ to 0.2. The immediate assessment problems could be solved with this technical fix; the retrospective pattern has improved considerably. The stock now appears to be slightly smaller, updated reference points are similar with the exception of Fmsy and Fpa which are now much lower. The advice based on Fmsy gives a slightly higher catch for 2022 than for the rejected assessment. Solving the biological problems with the assessment of this stock will inter alia require work on stock definitions and stock separation in the catches and surveys. It is expected that such data will be available for the next benchmark planned for 2023.

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

NWWG

Series

ICES Scientific Reports

Volume

3

Issue

88

Contributors (Editors)

Christopher Zimmerman

Contributors (Authors)

Tanja Bågø Buch; Höskuldur Björnsson; Jesper Boje; Frank Farsø Riget; Ruth Fernández; Rasmus Hedeholm; Einar Hjörleifsson; Teunis Jansen; Anders Nielsen; Anja Retzel; Karl-Michael Werner Christopher Zimmerman

ISSN

2618-1371

Recommended citation

ICES. 2021. Inter-Benchmark Protocol on East and Southwest Greenland Cod 2 (IBPGCOD2). ICES Scientific Reports. 3:88. 75 pp. https://doi.org/10.17895/ices.pub.8288