The Workshop for the review of the assessment of a new rebuilding plan for Western Horse Mackerel (WKWHMRP)

The Workshop for the review of a new rebuilding plan for Western Horse Mackerel (WKWHMRP) evaluated a rebuilding plan as proposed by PeLAC during three virtual meetingsin February and March 2021. The review was based on a technical report submitted by PeLACas well as additional analysis under the remit of WKWHMRP. Two independent reviewers concludedthat all ToR were adequately covered and that the minimum requirements for simulationtesting HCRs, as developed by WKGMSE process, were met.The tool used was based adaption of the ICES standard software package EqSim to include alternativeharvest rules with optional stability mechanisms, incorporate uncertainty in initial conditionsand generate additional outputs for model validation and HCR performance. The startingconditions were based on the 2020 ICES stock synthesis assessment. Alternative more pessimistic2014-2018 recruitment scenarios were explored. An assessment based on SAM forecastmethod was used as an alternative exploratory tool.The simulation results indicate that the proposed plan offers the potential for rebuilding of thestock by 2028, with rebuilding considered to be achieved when the stock size has exceeded Bpawith a 50% probability for three consecutive years. Risk to Blim falls below 5% by 2025. The alternativerecruitment scenarios showed rebuilding potential although the time frame in the mostpessimistic, although unlikely these scenarios indicated that the time frame may be longer thanten years.