Trophic relationships between a native and a nonnative predator in a system of natural lakes
Meeuwig MH, Guy CS, Fredenberg WA. 2011. Trophic relationships between a native and a nonnative predator in a system of natural lakes. Ecology of Freshwater Fish. 20(2):315-325
Abstract –Bull trout, a species of char listed as threatened under the US Endangered Species Act, have been displaced from portions of their historic range following the introduction of nonnative lake trout. It has been suggested that competitive exclusion as a result of trophic overlap between bull trout and lake trout may be the causal mechanism associated with displacement of bull trout. This study used stable isotope data to evaluate trophic relationships among native bull trout, nonnative lake trout and other fishes in seven lakes in Glacier National Park (GNP), Montana. Bull trout and lake trout had greater d15N values relative to other fishes among lakes (d15N ‡ 3.0&). Lake trout had greater d15N values relative to bull trout (d15N = +1.0&). Bull trout had greater d13C values relative to lake trout in six of the seven lakes examined. Although both bull trout and lake trout had greater d15N values relative to other fishes within lakes in GNP, differences in d15N and d13C between bull trout and lake trout suggest that they are consuming different prey species or similar prey species in different proportions. Therefore, displacement of bull trout as a direct result of complete overlap in food resource use is not anticipated unless diet shifts occur or food resources become limiting. Additionally, future studies should evaluate food habits to identify important prey species and sources of partial dietary overlap between bull trout and lake trout.
- Type
- Journal Article
- Authors
- Meeuwig, Michael; Guy, Christopher; Fredenberg, Wade
- Units
- GLAC
- Keywords
- Bull Trout, competitive exclusion, Lake Trout, Native Fisheries, Non-Native Species, Salvelinus confluentus, Salvelinus namaycush, stable isotope analysis, trophic relationship