The snow crab (Chionoecetes opilio) sustains an important bottom trawling fishery in the Sea of Japan. Its response to global warming is attracting the attention of the public. Using a transport and survival model for crab larvae in the Sea of Japan, we examined the spatial-temporal variations of crab spawning and larval settlement in the past (mid-20th century), present (early 21st century), and future (mid- and late 21st century) under the low and high radiative forcing scenarios. It was found that the variations in spawning differed between the regions south of and north of 41.5° N, on both seasonal and long-term scales. Larval settlement in the Sea of Japan was projected to increase in the future, which is mainly attributed to a reduction in mortality due to the low water temperature. Moreover, the aggregating location of the settled megalopae will likely shift northward, with increasing settlement off Hokkaido Island. With additional sensitivity experiments, we confirmed that the change in water temperature has a stronger impact on larval settlement than that in the current field. The change in water temperature controlled both the amount and distribution of crab larval settlement, while a change in current field only affected the distribution to some extent.
RESEARCHES OF THE RED SNOW CRAB CHIONOECETES JAPONICUS (DECAPODA, MAJIDAE) IN THE SEA OF JAPAN. 4. DIVISION OF THE AREA BY SIZE STRUCTURE VARIABILITY ANALYSIS