The Spatial Relationship between the Distributution of Ommastrephes Bartrami and Marine Environment in the Western North Pacific Ocean

In this study, we consider the effects of marine environmental factors on the spatial distribution of Ommastrephes bartrami in the western North Pacific Ocean during the period in which the commercial squid fishery operates. Spatial referenced fishery data and satellite-derived advanced very high resolution radiometry (AVHRR) sea surface temperature (SST) data, Sea-viewing Wide Fieldof-view Sensor (SeaWiFS) Chlorophyll a data and the yield data collected from fishery companies were examined using geographic information system (GIS) techniques. The distribution and relative abundance of O. bartrami were examined for the period 19952001. The results indicate that the O. bartrami fishery distributed west-eastwards extensively within the Kuroshio Extension and Kuroshio-Oyashio transition regions and two consistent areas of high abundance of O. bartrami were observed to the north-east of Hokkaido and close to the boundary of Japan and Russia. To understand spatial-temporal change of fisheries, the migration route of jig fleets is also mapped. Further, composed maps of SST range and averaged Chlorophyll-a concentration show the sea conditions around fishery. Sea gradients (SST gradients, chlo-a gradients) were used as indicators of mesoscale oceanographic activity and compared with the location of the fishery. It appears that O. bartrami fishery was associated with areas of thermal gradients and Chlorophyll-a concentration gradients, commonly seen at the interface of Kuroshio and Oyashio water. Finally, these results illustrate the insights which can be achieved by combining yield data of O. bartrami with concurrent remotely sensed environmental data. * Correspondense. E-mail: [email protected].