Image Processed Vertical Distribution of Water Temperature at the Squid Jigging Stations with a Poor Catch in the Japan Sea

Abstract

The data base of digital images of good catch conditions is not sufficient, but that of poor catches is indispensable to apply the vertical distribution of water temperature to fishing information system in order to decide the position of squid jigging in the Japan Sea. The 63 stations yielding less than 200 squids in more than 4 hours consecutive swings were sorted out, as the examples of poor catch conditions among 416 jigging records from 1982 to 1988. In this report, the data base of digital images of poor catches was examined by the group average method of cluster analysis. As for the results, the digital images of poor catches having mutually high similarity were pigeonholed into 15 small groups (=clusters) although there remained 17 independent images, and they were then divided into 2 large groups, which were in relation to the area division in the Japan Sea. Some small clusters consisted of the digital images within the same year, their component images were from one of the two areas and within 30 calendar days. Other clusters consisted of those in the different years, but the individual images in each of them were also from the same area and within 30 calendar days. This tendency is helpful in quasi-real time application of the data base of the fishing information system on board. On the basis of the results, a general flow chart for fishing information system was proposed. © 1991, The Japanese Society of Fisheries Science. All rights reserved.