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SFS Annual Meeting

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GUT CONTENT MASS VS. INDIVIDUAL BODY MASS: IS THERE A PREDICTABLE RELATIONSHIP IN PREDATORY STREAM FISHES?

Gut contents have been used to understand feeding behavior and to predict trophic position across fish populations. Gut fullness has received less attention but may be an important indicator of bottom-up regulation. Metabolic theory predicts that the rate of consumption of energetic resources is a power-law function of body mass. Larger individuals have lower mass-specific metabolic rates that may allow them to eat less frequently or otherwise utilize energetic resources more efficiently. This fundamental relationship provides a potential mechanism to link the sizes of individual fishes and, by extension, population size to the availability of energetic resources. Using predatory fishes from three different streams located in Washington, Oregon, and California, we tested the hypothesis that gut fullness is a predictable function of body mass. Sampled fishes were frozen and returned to the lab, where gut contents were surgically extracted and weighed. Linear regression will be used to determine whether a power-law relationship exists between gut content mass and body mass, as predicted by metabolic theory. This relationship will also be compared across study sites to assess whether local environmental conditions influence this relationship.

Vanessa Czeszynski (Primary Presenter/Author), University of Wisconsin La Crosse, vanessa.czeszynski@gmail.com;


Daniel McGarvey (Co-Presenter/Co-Author), Virginia Commonwealth University, djmcgarvey@vcu.edu;