ENVIRONMENTAL GRADIENTS AFFECT RAINBOW-TROUT POPULATIONS AMONG LAKES AND RESERVOIRS IN WYOMING

We defined relations of environmental variables and fish community fea tures to statistics of samples of rainbow trout Oncorhynchus mykiss fr om lakes and reservoirs in Wyoming. The mean length of rainbow trout i n gill-net samples was most strongly related to physical features, inc luding elevation, measures of water chemistry, and lake morphology. In dices of abundance and biomass of rainbow trout were related to the pr oportion of other fish species in gill-net samples, as well as elevati on, water chemistry, and lake morphology. Environmental gradients asso ciated with changes in elevation appeared to have substantial influenc e on the population structure and abundance of rainbow trout in lakes and reservoirs in Wyoming.