Abstract: We analyzed the fishery resource and environmental data collected from four trawl surveys conducted in southern Yellow Sea and East China Sea during autumn 2018, winter 2019, spring 2019 and summer 2019, aiming to understand habitat suitability and environment characteristics of Todarodes pacificus in southern Yellow Sea and East China Sea, elucidate the seasonal variations and environmental drivers of suitable habitats, and promote rational utilization and scientific management of T. pacificus. The temporal and spatial variations of the suitable habitat in the southern Yellow Sea and the East China Sea in different seasons were analyzed based on habitat suitability index. The contribution rate of various environmental factors to suitable habitats was analyzed using boosted regression tree model. The migration path of T. pacificus was deduced by combining the seasonal changes of suitable habitat. The results showed that the optimal surface temperature, surface salinity, bottom temperature, bottom salinity, and water depth for T. pacificus were 9.8-27.5 ℃, 23.2-34.3, 8.9-20.2 ℃, 31.6-34.7 and 56-133 m, respectively. The environmental preference of T. pacificus displayed significant seasonal variations. The suitable habitats showed a south-north cycle throughout the year, which were mainly concentrated in middle-northern East China Sea and offshore of southern Yellow Sea. The contribution rate of water temperature to the suitable habitats was the largest, followed by salinity and depth. In conclusion, the suitable habitats of T. pacificus were different across seasons in southern Yellow Sea and East China Sea. T. pacificus migrated northward or southward into the feeding grounds and spawning grounds. Temperature was the most important environmental driver of the suitable habitats.

Key words: Todarodes pacificus, habitat, environment characteristic, southern Yellow Sea, East China Sea.