International Council for the Exploration of the Sea
WKPRAWN 2022.pdf (14.6 MB)

Benchmark workshop on Pandalus stocks (WKPRAWN)

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posted on 2022-05-09, 08:34 authored by ICESICES

Benchmark results

Northern shrimp (Pandalus borealis) in divisions 3.a and 4.a East (Skagerrak and Kattegat and northern North Sea in the Norwegian Deep)

An ensemble model was developed to incorporate uncertainty in natural mortality (SS3 model). A distribution of possible natural mortalities at age was constructed based on a suite of M life history and other type models. Three M scenarios were developed: a low, median and high M. An objective weighting approach was used based on model performance statistics and diagnostics to develop the final assessment. The reference points were estimated using a shortcut MSE approach testing a range of fishing mortalities and biomass thresholds in relation to virgin stock size (B0). 

Northern shrimp (Pandalus borealis) in subareas 1 and 2 (Northeast Arctic)

For the Barents Sea stock, the accepted assessment model fell on SPiCT. The commercial CPUE used in the assessment was thoroughly investigated and standardized using a non-spatial model. A spatio-temporal modelling approach (sdmTMB) for the joint Norwegian/Russian Barents Sea Ecosystem Survey (BESS) was presented and compared to the design-based estimators currently used. There was some retrospective error on F/Fmsy but Based on the presented diagnostics, the reference model was considered adequate and acceptable. The standard approach for short-term forecasts and reference points was agreed.

Flemish Cap shrimp (NAFO Div. 3M)

There was limited progress on the Flemish Cap stock (pra.27.3M). An excellent long-term EU survey from 1988-present is available for the stock covering the period of the moratorium. This shows an increase from 2016 to 2019 with a subsequent decrease. Length-composition data are also available from the survey for this assessment. In future, it may be possible to explore an SS3 model for this stock given the partial and patchy nature of the available data.


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)

Colm Lordan • Johan Lövgren

Contributors (Authors)

Michael Wall Andersen • Tanja Baagoe Buch • Sergey Bakanev • Krista Baker • Mikaela Bergenius Nord • Patrik Börjesson • Tanja Baagoe Buch • Anndorte Burmeister • Massimiliano Cardinale • José Miguel Casas Sanchez • Ole Ritzau Eigaard • Chris Griffiths • Carsten Hvingel Francesco Masnadi • Katja Norén • Alessandro Orio • Mark Simpson • Katherine Skanes Guldborg Søvik • Fabian Zimmermann



Recommended citation

ICES. 2022. Benchmark workshop on Pandalus stocks (WKPRAWN). ICES Scientific Reports. 4:20. 249 pp.