Incorporating uncertainty into the estimation of the biological reference points F_0.1 and F_max for the Maine green sea urchin (Strongylocentrotus droebachiensis) fishery

The status of the Maine green sea urchin (Strongylocentrotus droebachiensis) fishery has not been quantitatively determined, despite its commercial importance and declining stock abundances. The high levels of natural variability in the population, and the uncertainty implicit in all fisheries, make it essential to determine probabilistic estimates of current fishing mortality rate and biological reference points for a reliable stock assessment. We used a Monte Carlo simulation approach to investigate how uncertainties associated with yield per recruit parameter estimation would affect F _0.1 and F_max and to identify their impacts on the determination of stock status. We found that higher levels of uncertainty increased variation in F_0.1 and F_max estimates, which translated to a decrease in the probability that the fishery was defined as overfished. F_0.1 was considered more appropriate as a target biological reference point, but the probability that the fishery would be defined as overfished varied by confidence level and the magnitude of uncertainty. We suggest that further investigations into other reference points be conducted before final selection and implementation of a management target for the Maine sea urchin fishery.