2020 Volume 68 Issue 3 Pages 243-251
Characteristics of the population dynamics of bluegill Lepomis macrochirus were studied in the south basin of Lake Biwa in 2009-2018. The bluegill CPUE in set nets during April to July fluctuated in the range of 1.9-30.2 kg/set net/day. According to multiple regression analysis, the largemouth bass (Micropterus salmoides) CPUE was detected as a negative factor, and the previous year’s water transparency reflecting the state of submerged macrophyte biomass was detected as a positive factor in relation to changes in bluegill CPUE. It was considered that the abundance of submerged macrophyte, which serve as hideouts for small bluegill, and the abundance of largemouth bass as predators were related to bluegill abundance. In addition, the size composition, and the nutritional condition of age-0 bluegill in the fall fluctuated annually, so it is necessary to clarify the relationship between the size and condition of the fish and overwinter mortality.
