Main content area

Spawning salmon increase brook trout movements in a Lake Michigan tributary

Janetski, David J., Moerke, Ashley H., Chaloner, Dominic T., Lamberti, Gary A.
Ecology of freshwater fish 2011 v.20 no.2 pp. 209-219
Salvelinus fontinalis, Salvelinus namaycush, ecosystems, eggs, energy, energy metabolism, environmental impact, models, monitoring, salmon, spawning, streams, temperature, trout, Lake Michigan
- Salmon and trout have been introduced to many ecosystems worldwide, yet the ecological impacts of salmonid introductions remain poorly understood. We investigated the effects of introduced Pacific salmon on stream-resident fish in the Great Lakes basin by monitoring the movements of passive integrative transponder (PIT)-tagged brook trout in a Lake Michigan tributary receiving a salmon spawning run and in a nearby stream not receiving salmon. Coincident with the September arrival of salmon, an estimated 52% of resident brook trout moved >200 m, while no such movements were detected in the nonsalmon stream. After 3-4 days, however, brook trout movement patterns became similar in the two streams, suggesting that salmon effects on brook trout movements were short-lived. Movements in the salmon stream were predominantly upstream in direction, with 50% of the tagged brook trout travelling from below to above the stationary PIT tag readers during the study. Declining water temperatures with the onset of fall coincided with low levels of brook trout movement at both sites, likely due to relocation for spawning. Increased brook trout movements coincident with the arrival of salmon spawners could be driven by a combination of interference competition and egg consumption. Using a bioenergetics model, we estimated that the energy lost to movement was likely compensated by the energy obtained from consuming salmon eggs. We conclude that salmon spawners can substantially increase brook trout movement, but in our study, these effects were short-lived and likely negligible from a bioenergetics perspective.