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Food and Feeding Preferences of Rainbow and Brown Trout in Southern Appalachian Streams
Glenn F. Cada, James M. Loar and David K. Cox
The American Midland Naturalist
Vol. 117, No. 2 (Apr., 1987), pp. 374-385
Published by: The University of Notre Dame
Stable URL: http://www.jstor.org/stable/2425980
Page Count: 12
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The stomach contents of Age 1 and older rainbow (Salmo gairdneri) and brown trout (S. trutta) in five southern Appalachian soft-water streams were compared with concurrent drift samples. A wide range of food items was consumed, and no prey genus comprised an average of more than 2.5% by number of the diet of either trout species. Seasonal changes in composition of drift from June to November were generally mirrored by shifts in trout diets. The contribution of terrestrial organisms to drift and to diets was highest in late summer and autumn. Averaged over all samples, terrestrial taxa comprised 36, 45 and 50% of the drift, rainbow and brown trout diets, respectively. Both trout species exhibited statistically significant feeding preferences for particular taxa (notably terrestrial organisms), but most prey were consumed in proportions similar to their abundance in the drift. Opportunistic feeding lends stability to trout populations in streams with relatively low autochthonous food production by allowing trout to capitalize on terrestrial input. Our findings emphasize the importance of both protecting riparian vegetation (which is a source of terrestrial prey) and considering aquatic habitat elements in which trout can efficiently capture surface drift when determining minimum stream flow requirements for water-diversion projects.
The American Midland Naturalist © 1987 The University of Notre Dame