東北海域における南下期のカツオ漁場形成とその判別分析

Abstract

The formation of southbound skipjack fishing grounds off Touhoku sea area was studied through the use of satellite imageries and satellite-aided issues by JAFIC covering the recent six years. It was verified that the two conditions of “to be close to the warm core ring off Sanriku or the SST (sea surface temperature) boundaries” were essential to the formation. Then, by quantifying those conditions, the method to discriminate and predict the formation of fishing grounds was studies.The discriminant variables were 1, the spatial and 2, the temporal SST gradients of a sample mesh and 3, the proximity to the current path within a warm core ring or to the SST boundary, respectively, divided by the deviation of the present SST from the favourable water temperature. On meshes sampled from the sea areas, data of variables were obtained and subjected to discriminant analysis.Within the discriminant model thus obtained, plus sign of composite variable of a mesh discriminates and indicates that a fishing ground for skipjack is formed in the sea area represented by the mesh. The mean correct discrimination rate reached 88% for used data and 82% for new data and proved its usefulness.