Summer Food Habits of Yellow Bass and Black Bullheads in Clear Lake

Young yellow bass Roccus mississippiensis, ate primarily entomostracans but started taking significant numbers of immature insects when the bass reached 50 mm, total length. Adult yellow bass showed little change in food habits with increase in size from 5 to 7.9 inches with immature insects and crustacea in 60 and 81 per cent of the stomachs, respectively. Forage fish were found in only 2 per cent of the yellow bass in 1960 compared with 24 per cent in 1952 and 86 per cent in 1943 when the yellow bass were larger. Cladocera decreased in frequency in yellow bass stomachs from June to August, 1960. The highest frequencies of copepods, Hyalella, and immature insects occurred in July. The daily period of maximum feeding appeared to be 4 to 8 PM with maximum activity, as measured by gill net catches from 6 PM to 2 AM. Black bullheads, Ictalurus melas, ate similar foods to the yellow bass except for a greater utilization of forage fish