Yearly Fluctuation of Food Habits of the Isaza, Chaenogobius isaza, in Lake Biwa
1984 Volume 45 Issue 4 Pages 279-288
Details
1984 Volume 45 Issue 4 Pages 279-288
The stomach contents of the Isaza, Chaenogobius isaza TANAKA, were investigated in Lake Biwa from 1962 to 1982. In the present study, yearly fluctuation of food habits was observed.
The fish of age 0 fed mainly on zooplankters, such as Daphnia longispina, Diaphanosoma brachyurum, Mesocyclops leuckarti, Leptodora kindtii, throughout the year before 1970. However, they fed mainly on gammarids from winter to spring after 1970.
The fish of age 1 also fed mainly on zooplankters, gammarids and chironomid larvae throughout the year before 1970. However, they fed mainly on gammarids after 1970. The frequency rate of gammarids in stomach contents was about 45% to 84%, and the rates were always higher than for other stomach contents.
The authors noted that the yearly change of food habits of the Isaza was affected by the eutrophication of Lake Biwa.
