Spawning Per Recruit analysis for female snow crab Chionoecetes opilio in the sea off Kyoto prefecture

Abstract

Analysis of Spawning Per Recruit (SPR) has been used to evaluate the effect of the fishing mortality on the spawning ability of the stock. We analyzed fishery data on snow crab Chionoecetes opilio by using this technique. This stock is managed by seasonal protected area. Before the protected area was introduced, the stock was at about 1.1% of the maximum possible spawning stock biomass per recruit. By the protected area, %SPR of this species has improved to 4.2%, nearly four times larger than before. We also examined the effect of changing the fishing gear from Danish seines to traps. Since traps are more selective, we can decrease bycatch mortality by using a trap instead of a Danish seine. Our analysis suggested that we can enhance %SPR to 13.8% by using traps.