河川(主として木曾川および揖斐川)の異常流出が伊勢湾のカタクチイワシ漁況におよぼす影響について

Abstract

The influences of the excessive flows of the river upon the catches of anchovy in Ise Bay were studied in analizing the data of discharge of the Rivers Kiso and Ibi, which have great influences on the variation of the sea condition of this bay, of the oceanographic observations, and of the daily fishery records of ten-odd boats sampled from each fishing port on Ise Bay. The results obtained are summarized as follows: 1) Within three days after the excessive flow breaks out influence of the fresh water extends to the south part of Ise Bay along its west side at the surface. At the depth of 5m the influence seems to take place in about seventh day and to continue to about fifteenth day after the beginning of flow. 2) In one or two days after the excessive flow breaks out, the northern limit of fishing ground and the position of its centre move southwards. With abating of the flow they go the former state. Their locomotion in the direction of east and west is not so evident as one in the north and south. 3) Generally the catches of anchovy show a tendency to decrease after the excessive flow, and in most cases the minimum catch appears in the period from first to fifth day after beginning of the flow in the northern parts of Ise Bay and from sixth to fifteenth day in the middle and southern parts.