동해 명태의 생태학적 특징 변화와 어업 생산량의 변화

Abstract

Walleye pollock (Gadus chalcogrammus, hereafter pollock) was one of the most dominant species in Korean waters, but its stock has rapidly decreased since the late 1980s and collapsed completely in the early 21st century. In this study, we investigated how the decrease in biomass related to growth and maturity of pollock using biological data including length, weight, and gonad weight of pollock collected for 31 years from 1973 to 2003 in the fishing area in Korean waters. A frequencyhistogram of pollock length indicated that the size was smaller before the late 1980s,when the biomass was larger, while the size became larger after late 1980s when the biomass was smaller.In addition, zooplankton biomass was inversely related with the biomass changes in the late 1980s: zooplankton biomass was smaller when the pollock biomass was larger, vice versa. These relationships suggest that feeding competition may contribute to the size change of pollock. In relation to the pollock biomass changes, we will also present physical environmental changes including stratification and the wind.nvestigated how the decrease in biomass related to growth and maturity of pollock using biological data including length, weight, and gonad weight of pollock collected for 31 years from 1973 to 2003 in the fishing area in Korean waters. A frequencyhistogram of pollock length indicated that the size was smaller before the late 1980s,when the biomass was larger, while the size became larger after late 1980s when the biomass was smaller.In addition, zooplankton biomass was inversely related with the biomass changes in the late 1980s: zooplankton biomass was smaller when the pollock biomass was larger, vice versa. These relationships suggest that feeding competition may contribute to the size change of pollock. In relation to the pollock biomass changes, we will also present physical environmental changes including stratification and the wind.