Length-based stock assessment and fisheries management of hair crab Erimacrus isenbeckii in Funka Bay, Hokkaido, Japan

The hair crab fishery in Funka Bay, Hokkaido, has adopted a total allowable catch system. In order to examine management policy, a length-based population analysis (LPA) including yield per recruit (YPR(L)) was conducted on the hair crab in Funka Bay. LPA is effective for assessing fish stocks with uncertain aging characteristics. YPR(L) was developed for this study, as a method of calculating the YPR using parameters for each length class, which are estimated by LPA, instead of parameters for each age. The LPA model followed the population dynamics of this stock. Estimated abundance remained comparatively stable, but showed no recovery trend. As a result of YPR(L), the fishing mortality coefficient, which is used for calculating total allowable catch, was 60% of F0.1, a sufficiently safe value. Consequently, we concluded that fisheries management should continue to be based on the existing reference points.