. Bulletin. Natural history; Natural history. 70 80 90 100 110 120 130 110 150 160 170 180 190 200 "220 210 260 280 300^ 1(5o 5(i0 600 700 FISH TOTAL LENGTH (mm) Fig. 2,—Average weight percentages of major foods found in channel catfish of different lengths from the intake and discharge arms of Lake Sangchris during 1974 and 1976. that consumption of plants was greatest from April to June. Insects generally con- tributed more to the catfish diet during the rest of the year. Seasonal compari- sons were believed not very accurate, because they were highly influenced by the number of fish sa
. Bulletin. Natural history; Natural history. 70 80 90 100 110 120 130 110 150 160 170 180 190 200 "220 210 260 280 300^ 1(5o 5(i0 600 700 FISH TOTAL LENGTH (mm) Fig. 2,—Average weight percentages of major foods found in channel catfish of different lengths from the intake and discharge arms of Lake Sangchris during 1974 and 1976. that consumption of plants was greatest from April to June. Insects generally con- tributed more to the catfish diet during the rest of the year. Seasonal compari- sons were believed not very accurate, because they were highly influenced by the number of fish sampled and their sizes. Channel catfish from the intake and discharge arms of Lake Sangchris ate similar foods. Diets depended more on the size of the specimen than its particular location in the lake or the season of its capture. Results showed that plant or animal matter could provide a substan- tial part of the diet for a reproducing population of channel catfish and that a shift from one type of food to another normally accompanied growth. Small channel catfish consumed insects and therefore, competed with all other fishes in Lake Sangchris that possessed an insec- tivorous phase in their life histories. Com- petition with other fishes for forage fish or crayfish appeared limited to large channel catfish. Plants, therefore, were one main food upon which channel cat- fish could subsist during the change of diet from primarily insects to fish and crayfish. The only difference observed in food habits of channel catfish from the two arms of Lake Sangchris was a greater consumption of insects in the intake arm of the lake, attributed to greater insect availability. FRESHWATER DRUM Of the 259 freshwater drum collected for stomach analysis from May 1974 through October 1976, 39 percent (101) were from the intake arm, while 61 per- cent (158) were from the discharge arm. They ranged in total length from 105 to 372 mm (mean, 191 mm) in the intake arm and from 52 to 349 mm (mean, 17
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