Report of the Workshop on Blue Whiting (Micromesistius poutassou) Long Term Management Strategy Evaluation (WKBWMS)

• Main Author: ICES (11907872)
• Format: Report
• Language: unknown
• Published: 2016
• Subjects: Fisheries and aquaculture; Pressures; impacts; conservation; and management; Micromesistius poutassou; blue whiting; WKBWMS; CM 2016/ACOM; management strategy evaluation (MSE); long-term management strategy; Northeast Atlantic
• Online Access: https://doi.org/10.17895/ices.pub.19284668.v1

The Workshop on Blue Whiting Long Term Management Strategy Evaluation (WKBWMSE) was hosted at ICES headquarters on August 30, 2016. The aim of the workshop was to re-evaluate biological reference points and evaluate a proposed long-term management strategy (LTMS) for the Northeast Atlantic blue whiting (BW, Micromesistius poutassou) stock (whb-comb; Subareas 1–9, 12 and 14). This was done in a response to a recommendation from the Inter-Benchmark Protocol of Blue Whiting, where a new assessment of the stock was produced, and a NEAFC request to ICES. There were 20 participants from 10 countries: 18 scientists and 2 industry representa-tives. Two reviewers reviewed the analytical work and the conclusions of the workshop. See full participant list in Appendix 1. A stochastic simulation model, R-package called “EQSIM”, was used to evaluate the biological reference points and the LTMS. Two characteristics of the input data were identified that could influence the simulations: highly variable recruitment, with peri-ods of high and low productivity, and high uncertainty in the stock assessment. Re-cruitment is a keystone variable in LTMS as it has a large impact on the potential yield that can be taken from a fish stock. There is no relationship between BW spawning stock biomass (SSB) and recruitment, but there is relationship between recruitment and SSB two years later. BW recruitment, from 1981 to 2016, is highly variable (the highest value is 17x the lowest value) and has one period of high recruitment, from 1996 to 2005, causing high auto-correlation in estimated recruitment. WKBWMSE agreed that in the LMTS evaluation the whole recruitment time series should be used as there is no scientific reason to reject some years and accept others. The stock assessment depends primarily on a single acoustic index of abundance that in the past has had obvious year effects. This has led to notable retrospective revisions in estimates of stock size and fishing mortality (F). Past advice uncertainty, rather than parametric model ...