MATERNAL EFFECTS AND TIME TO RECOVERY

Abstract

The discovery of an age-dependent effect in black rockfish (Sebastes melanops Girard, 1856) raises questions about the impacts of fishing on population productivity and, by extension, the ability of overfished populations to recover. I used a simulation to investigate whether a population with an age-dependent effect will recover faster from overfishing than a population without one. The effect is modeled with a multivariate Beverton-Holt stock-recruitment model. This new stock-recruitment function is a modified version of the classic Beverton-Holt model. The parameters are chosen so that prerecruitment mortality and survival rates of offspring depend on the age of their mother, hereafter referred to as their maternal age. The development of the effect past the very early larval stage is unknown; this uncertainty is addressed by multiple hypotheses. Many scenarios were simulated and the results are presented as a summary. I found that populations with an age-dependent effect generally recovered faster than populations without one, but if the effect strongly affects density-dependent mortality of juveniles, then time to recovery might not improve with the addition of a effect and might increase. For most cases (85% of those tested) changes in recovery time were between an increase of 3 yrs and a decrease of 14 yrs. These simulation results show that an age-dependent effect may influence a population's ability to recover from an overfished state.