Satellite infrared observations of Kuroshio warm-core rings and their application to study of Pacific saury migration

Abstract

Satellite infrared observations of Kuroshio warm-core rings (KWCRs), made in the Tohoku area west of 150°E from February 1980 to June 1981, were used to study the effect of ring distributions on the migration routes of the epi-pelagic and migratory fish Pacific saury. Cololabis saira (Brevoort). The movement and mean speed of three KWCRs and a Tsugaru warm current gyre were determined in the study area. KWCRs tended to drift to the north or to the east at a mean speed of 5 cm s −1. This drift speed is similar to that of Gulf Stream warm-core rings, but the drift direction is quite different from the westward drift in the Gulf Stream system. A comparison between distribution of KWCRs and distribution of fish schools suggests that the KWCRs control southward migration routes of Pacific saury through interaction with the surrounding cold waters such as the First and Second Oyashio Intrusions. Satellite infrared monitoring of KWCRs and the surrounding cold waters have proved to be useful for the short period prediction of Pacific saury fishing ground formation.