DELINEATION OF MESO SCALE FEATURES IN THE KUROSHIO-OYASHIO TRANSITION REGION AND FISH MIGRATION ROUTES USING SATELLITE DATA OFF JAPAN

摘要

Kuroshio warm-core rings (KWCR) are invariably formed from the intensification of Kuroshio Extension transport heat, salt and biomass from lower to higher latitudes. The distribution pattern of these rings and other meso-scale features such as eddies, cold and warm streamers in Kuroshio-Oyashio transition region and their interaction results in the occurrence and migration of potential fisheries zones (PFZ). Past studies have shown that formation of fishery grounds and their migration attribute to warm and cold streamers entrained along the periphery of warm-core rings. In this paper combining NOAA-AVHRR, ADEOS/OCTS data and sea truth observations, we describe different meso-scale features and their interactions with surrounding water through local advection and streamer activities as well as how fish species utilize different range of temperatures and phytoplankton blooming areas for their migration. It is noteworthy that sardine schools use the warm streamers for their migration towards north from Kuroshio Extension to warm-core rings and from the warm-core rings to the coastal waters within a specific range of thermal and chlorophyll signature. Similarly, skipjack moves in a range of temperature (20.5 - 23.0°C) and pigment concentration (0.12-0.16 μg/l) in the Kuroshio region. The movement of fishing grounds associated with the warm-core rings and warm streamers are also discussed. It is concluded that the satellite information provides a space/time overview of different oceanographic features can profitably be utilized in delineating PFZ and increases our understanding how they are continually interacting.