Catch distribution of diamond squid (Thysanoteuthis rhombus) off Hyogo Prefecture in the western Sea of Japan and its relationship with seawater temperature

Abstract

This paper describes the distribution of catches of diamond squid (Thysanoteuthis rhombus) off Hyogo Prefecture in the western Sea of Japan, and the relationship between the fishing condition and seawater temperature based on the catchlocation and catch-amount data collected from the logbooks of seven vertical longline fishing boats in 1999-2005. Catches generally occurred south of 36°15’N, but in September-October of 2003 and 2005, when a cold water mass occurred on the fishing ground, catches were concentrated near shore south of 35°45’N. Good catches occurred where seawater temperatures at 50 and 100 m depths were>19°C and>14-15°C, respectively, from late August through early November in 1999-2005. The mean water temperature at 100 m depth at six oceanographic observation sites off Hyogo Prefecture was related to the mean latitude of catch locations weighted by catch amount, which suggests that this index can be used to forecast the location of the fishing grounds.