Studies on diet conditions and their feeding behaviors related to the production of Boleophthalmus pectinirostris in Ariake Sound

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In the 2ィイD1ndィエD1 year of this project, the establishment process of a territory by young of the year was studied using video notes taken in previous years, as well as the completion of the studies continued from the previous year on the relationship between their behavior and the tide, on the determination of the diatom stock size on the mudflat, and on the determination of the territory size.Young of the year come on to the mudflat in August, and first perform errant movements. They change their movement mode in time, and stay for some minutes to some ten minutes in a place where a tide pool is formed. The resident mode appears in October. Individuals in the resident mode repeat foraging within a certain area where a tide pool with a burrow is formed, and attack invaders. Conflicts also occur between neighboring territory owners. Fish with larger size do not always possess the priority in holding a territory, showing there is some extra condition, which determines the priority.The seasonal changes of the diatom stock size on the mudflat were irregular, although the change with time was large. The production of the food diatom does not seem to change only with the seasonal condition. However, the element which controls the production was not determined in this study. The comparison of the fatness of the mudskippers between habitats revealed that the fatness of fish was controlled not only by the abundance of the food but by unknown extra factor. The mudskipper occupy a certain area with food for the feeding ground. However, the adhesion of the fish to a territory would limit their migration even if the food availability in their territory is low, and the food availability is not always reflected in the fatness and the production of the mudskippers.