Should harvest control rules for male-only fisheries include reproductive buffers? A Bering Sea Tanner crab (Chionoecetes bairdi) case study

Abstract

Highly variable recruitment and a complex harvest strategy resulted in dramatic inter-annual changes in historical catches, including prolonged closure periods, for Bering Sea Tanner crab (Chionoecetes bairdi). Current management regulations, linked to recent frequent closures, led to an industry-initiated cooperative effort to reevaluate the harvest control rule (HCR) that forms part of the State of Alaska harvest strategy. Management strategy evaluation (MSE) was used to assess conservation and economic trade-offs of fifteen HCR options that differed in how females were considered. Several male-only HCRs performed similarly to those that accounted for females. However, the inclusion of both sexes reflected conservation and economic objectives while acknowledging the uncertainty around reproductive dynamics. The HCR selected by the Alaska Board of Fisheries included a threshold for opening the fishery based on mature male biomass (MMB), scalars based on relative levels of mature female biomass (MFB) and MMB that determine the exploitation rate on MMB, and a maximum exploitation cap on industry-preferred sizes of legal males. This work illustrates how manager-stakeholder collaboration may enable improved fishery management. Our analysis provided managers with a tool to facilitate productive and transparent dialogue with industry, with the goal of accounting for conservation and economic objectives, given some of the underlying biological uncertainty associated with reproductive dynamics. This study demonstrates that the inclusion of reproductive buffers in HCRs for male-only fisheries may be able to better achieve conservation goals without sacrificing economic performance.