Abundance and feeding habits of largemouth bass Micropterus salmoides in Haruna Lake, Gunma prefecture, Japan
2004
Kuge, T. (Gunma-ken. Fisheries Experiment Station, Maebashi (Japan)) | Nobusawa, K. | Maita, M.
Abstract: The abundance and feeding habits of largemouth bass Micropterus salmoides were investigated in Haruna Lake, Gunma, Japan. A total of approximately 2500 largemouth bass (total length >= 25cm) were estimated in 1997 by using mark-and-recapture method. Population hatched during 1995 - 1997 suggest the dominant year classes by age composition. Fish and crustacean were the important prey according to investigated stomach contents of 241 specimens. As regards preyed fishes, the main one was lake goby Rhinogobius sp. in 1997, the poor fishing year of pond smelt Hypomesus nipponensis, whereas pond smelt occupied the largest proportion in 2001, the bumper fishing year of it. The condition factor and stomach-content-somatic index were lowered in 1997, but increased in 2001. The body weight of largemouth bass in fishing tournament had been lowering during the poor fishing years, before recruitment of dominant year classes as weighed bodies. Therefore, it is suggested the poor abundance of pond smelt causes lack of bait for largemouth bass, and the increased population of largemouth bass affect the abundance of pond smelt by predation pressure to adult pond smelt in spring, the spawning season of pond smelt and young after summer in Haruna Lake.
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