International Council for the Exploration of the Sea
WGMG2013.pdf (2.8 MB)

Report of the Working Group on Methods of Fish Stock Assessments (WGMG)

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posted on 2013-01-01, 00:00 authored by ICESICES
The ICES Working Group on Methods of Fish Stock Assessment (WGMG) met in Reykjavik, Iceland from 30 September–4 October 2013. Work conducted prior to the meeting focused on aspects of the ICES data-limited stocks (DLS) framework; in par-ticular, how robust it is (in terms of delivering more conservative catch advice when less data are available) and whether the performance of some of its age-aggregated methods (e.g. for Category 3) can be improved by including in the Harvest Control Rule (HCR) either a confidence interval for the age-aggregated index used or the average length in the catch relative to some reference level. Indications are that the DLS framework does not always deliver more conservative catch advice when less data are available, and that the performance of HCRs can potentially be improved with additional auxiliary information. The development of generic HCRs, and the use of Fproxy values and targets in HCRs were also considered, and suggestions made for the preparation of survey indices for use in HCRs. Work conducted during the meet-ing itself included a comparison of a range of methods for estimating reference points when applied to two ICES datasets (North Sea cod and herring); for neither of these datasets was FMSY estimated consistently across models and SR forms, highlighting the challenges for estimating reference points from stock–recruit data. A brief review of current mixed fishery and multispecies approaches was conducted, and a recom-mendation provided for evaluating a mixed fishery approach under a minimum real-istic multispecies operating model. A summary of the workshop held as part of the World Conference on Stock Assessment Methods is provided, with a look forward to the possible future development of the simulation exercises conducted as part of the workshop.


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