An evidence-based approach for selecting a limit reference point for Pacific herring (Clupea pallasii) stocks in British Columbia, Canada.

A limit reference point (LRP) is defined as a level of biomass to be avoided with high probability, which should be selected to protect fish stocks from "serious harm". We present an evidence-based approach for diagnosing serious harm and apply it to the selection of LRPs for five Pacific herring (Clupea pallasii) stocks in British Columbia (BC). Natural mortality (M) is estimated to be time varying and has increased more than it declined over the past three decades, which presents a challenge for estimation of equilibrium reference points based on maximum sustainable yield. We present a semi-empirical approach for developing LRPs, which examines surplus production in relation to spawning biomass to determine whether there is evidence for low productivity, low biomass (LP-LB) states consistent with serious harm. Three stocks showed evidence of persistent LP-LB states that resulted in periods of fishery closures. Based on these results, an LRP of 30% of unfished spawning biomass (0.3B0) was recommended and adopted for management of all five major stocks of BC Pacific herring. [ABSTRACT FROM AUTHOR]