2016 Volume 80 Issue 3 Pages 207-213
Japanese anchovy Engraulis japonicas is one of the main species for fisheries in Ise Bay. The factors that contribute to changes in the Japanese anchovy biomass in the bay have not been identified. The ratio of the catch per unit effort of Japanese anchovy inside the bay to that outside the bay (biomass index) was calculated between 1978 and 2003 to reveal its interannual changes. The entry of Japanese anchovy into the bay along with the bay-mouth water was observed from 1978 to 1994 when the Kuroshio Current was offshore and a large meander occurred frequently; such a coincidence was not observed in the bay after 1995 when the Kuroshio Current was onshore and a large meander hardly ever occurred. From 1999 to 2003, we estimated the Japanese anchovy biomass each month using a quantitative echo sounder in the north-eastern waters of the bay, and investigated the zooplankton density. From July to September (i.e. the main fishing season), a positive correlation was found between the Japanese anchovy biomass and zooplankton density. This showed that the bay serves as a feeding ground for Japanese anchovy. Consequently, the influence of offshore water and prey availability are important for determining Japanese anchovy biomass in Ise Bay.
