Numerical studies on snow crab (Chionoecetes opilio) larval survival and transport in the Sea of Japan

The snow crab Chionoecetes opilio is an important fishery species in Japan. Hydrodynamics are vital to the distribution, recruitment and settlement of crab larvae in nursery areas. In this study, we developed a survival and transport model of snow crab larvae to investigate the interannual variability in larval settlement in three fishing areas: west of Toyama (region A), west of Niigata (region B) and west of Hokkaido (region C). We found that the female crab stock abundance determined the modeled number of zoea in regions A and B, whereas water temperature played a major role in the initial number of zoea in region C. As for larval settlement, the ocean current impacted settlement in region B, and water temperature was vital to settlement in region C. Both female crab abundance and hydrodynamics contributed to variability in settlement in region A. The results revealed contrasting recruitment patterns in the three fishing areas. Self-recruitment was the primary form in regions A and C, whereas both self-recruitment and recruitment from upstream sources were important in region B.