Migration of Yellowtail in Relation to Intrusions of Warm Water from the Kuroshio

Abstract

In the Kumano-nada and Enshu-nada Seas, warm water masses from the Kuroshio intrude into the coastal area depending on the paths type of the Kuroshio. Associated with the intrusions which occur with a period of 50 days from the Izu Peninsula when the Kuroshio takes the B-type path, yellowtail adults called buri migrate to the coastal area. However, the long time-lag between the intrusion and buri catch causes a negative relationship between the temperature and catch. The results suggest that the buri school migrates westward after the water mass has diffused. Since there is a positive relathionship between temperature and catch associated with very rapid intrusions when the Kuroshio takes the C-type path, it is necessary to distinguish oceanographic phenomena in order to understand the fish behavior in response to offshore oceanic changes. In addition, the seasonal horizontal temperature gradient should be considered when estimating the optimum temperature range for fish because the relative temperature change greatly affects fish migration rather than the optimum temperature. © 1994, The Japanese Society of Fisheries Science. All rights reserved.