Constraints of body size and swimming velocity on the ability of juvenile rainbow trout to endure periods without food
Abstract:The hypothesis that body size and swimming velocity affect proximate body composition, wet mass and size‐selective mortality of fasted fish was evaluated using small (107 mm mean total length, LT) and medium (168 mm mean LT) juvenile rainbow trout Oncorhynchus mykiss that were sedentary or swimming (c. 1 or 2 body length s−1) and fasted for 147 days. The initial amount of energy reserves in the bodies of fish varied with LT. Initially having less lipid mass and relatively higher mass‐specific metabolic rates caused small rainbow trout that were sedentary to die of starvation sooner and more frequently than medium‐length fish that were sedentary. Swimming at 2 body length s−1 slightly increased the rate of lipid catabolism relative to 1 body length s−1, but did not increase the occurrence of mortality among medium fish. Death from starvation occurred when fish had <3·2% lipid remaining in their bodies. Juvenile rainbow trout endured long periods without food, but their ability to resist death from starvation was limited by their length and initial lipid reserves.
Document Type: Regular Paper
Affiliations: 1: U.S. Geological Survey, Wyoming Cooperative Fish and Wildlife Research Unit, University of Wyoming, Laramie, Wyoming 82071-3166 U.S.A., 2: Department of Zoology and Physiology, University of Wyoming, Laramie, Wyoming 82071-3166 U.S.A. and 3: Department of Animal Science, University of Wyoming, Laramie, Wyoming 82071-3684 U.S.A.
Publication date: 2004-08-01