Fisheries Investigations – 06 Stomach Analysis

Fisheries Investigations in Crater Lake, Oregon, 1937-1940 by Arthur D. Hasler and D. S. Farner

Stomach Analysis


Table 7 – Stomach Contents of Salmonids in Crater Lake, 1940

During the summer of 1940, 79 stomachs were collected from fishes taken by anglers. Data on weight, length, and sex were recorded, and ages determined by examining the scales. No differences in food habits could be noted between the two species or among the various age groups within each species.

Apparently the relative amounts of the various items in the diet depend upon the availability of these foods (Table 7). In August there were many terrestrial insects floating on the lake surface and these constituted a much larger proportion of the diet than in July when very few were observed. Brode (1938) found that Daphnia made up a considerable part of the diet of both species. One stomach collected in 1940 contained Daphnia. Furthermore, noDaphnia were found in tow-net samples from 100 meters to the surface, and none was found in Fumerole Bay where numbers were reported by Hasler (1938).

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