Temporal change in catches and resources of icefish Salangichthys microdon in Lake Abashiri, eastern Hokkaido, Japan

Abstract

We investigated the mechanism of temporal changes in yearly catches and resources of icefish Salangichthys microdon in Lake Abashiri from 1936 to 2007. Icefish have lived in Lake Abashiri since the early 1930s because of climate change and topographical features, and have been caught by commercial fisheries. Their population size fluctuated annually from 1 to 94 tons. The periodicity of one-year intervals relating to the life-history of icefish was observed in yearly catches. Population sizes at the beginning of each fishing season were estimated to be 36,763 × 103-487,590 × 103 individuals based on the daily CPUE and the density of juveniles. The icefish seem to be stimulated to migrate seaward by rising water and flooding, resulting in an abrupt decline in commercial catches and high spawner abundance in the following year. The relationship between the number of adults and recruitment fitted well to Ricker's reproduction model.