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 meetings in February and March 2021. The review was based on a technical report submitted by PeLAC as well as additional analysis under the remit of WKWHMRP. Two independent reviewers concluded that all ToR were adequately covered and that the minimum requirements for simulation testing HCRs, as developed by WKGMSE process, were met.

The tool used was based adaption of the ICES standard software package EqSim to include alternative harvest rules with optional stability mechanisms, incorporate uncertainty in initial conditions and generate additional outputs for model validation and HCR performance. The starting conditions were based on the 2020 ICES stock synthesis assessment. Alternative more pessimistic 2014-2018 recruitment scenarios were explored. An assessment based on SAM forecast method was used as an alternative exploratory tool.

The simulation results indicate that the proposed plan offers the potential for rebuilding of the stock by 2028, with rebuilding considered to be achieved when the stock size has exceeded Bpa with a 50% probability for three consecutive years. Risk to Blim falls below 5% by 2025. The alternative recruitment scenarios showed rebuilding potential although the time frame in the most pessimistic, although unlikely these scenarios indicated that the time frame may be longer than
ten years.