Workshop on Data-limited Stocks of Short-lived Species (WKDLSSLS)
The Workshop on Data Limited Stocks of Short-Lived Species aimed to provide guidelines onthe estimation of MSY proxy reference points for category 3–4 short-lived species and to evaluatethe management procedures currently in use and their appropriateness for short-lived speciesby means of Long-Term Management Strategy Evaluations (LT-MSE).
In relation to assessment methods for short-lived data-limited stocks and estimation of biologicaland MSY proxy reference points, the WK focused on the application of SPICT (Pedersen andBerg, 2017). The WK was updated on recent improvements of SPiCT and the harvest controlrules (HCRs) used to manage stocks after WKLIFE VII and VIII by including either the MSYfractileor MSY-PA rules. For the optimal SPiCT advice rule, users should refer to the updateICES guidelines. Work on fitting SPICT to case studies was made before and during the workshop:Assessments to Anchovy in 9.a South resulted in a satisfactory fitting of SPICT, whilst fits to Anchovy in 9.a West and to Sprat 7.de were still unsatisfactory. In addition, there were some presentations on applications of SPiCT to several Cephalopod populations. Length-based indicatorsof stock status were discarded as generally they are not suitable for short-lived species where recruitment induces major interannual changes in the length distribution of catches. A provisional application of a two-stage assessment was presented for Sprat in 7de, but resultswere still provisional.
In relation to the evaluation of management procedures for these stocks, MSE testing of harvestcontrol rules based on trends of biomass indices were analysed for anchovy-, sprat-, and sardine like stocks including several operating models. All simulations showed that the shorter the lagbetween observations, advice and management, the bigger the catches and the smaller the risk.This implies that In-year advice should always be preferred over the normal calendar (with aninterim) year advice for these stocks. Major drivers of risks are by order of relevance: historicalexploitation level (and trajectory), and the harvest control rule (HCR) with its selected UncertaintyCap (UCap). This emphasizes the relevance of trying an initial assessment of the relativestatus of the stock regarding optimal exploitation to judge if a precautionary buffer is requiredto start management. Further work on the assessment of past exploitation level is required.
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