Bottom-Up Effects of Increased Sedimentation on Brown Trout (/Salmo trutta/) Fisheries

Abstract:

Caldwell Creek is a historic brown trout (Salmo trutta) fishery in Northwest Pennsylvania that has seen significant declines in population quality. Significant restorations have been conducted throughout the watershed, however, they have yet to prove successful in restoring the fishery. Anthropogenic land use changes have caused an increase in sedimentation in Caldwell Creek. However, no mechanism linking the increase in sedimentation to the decline of the brown trout fishery has been proposed. We hypothesize that increased sedimentation has degraded brown trout habitat and has had a bottom-up effect on the ecosystem through the macroinvertebrate community. Analysis of habitat quality will be conducted using ArcGIS, and macroinvertebrates assemblage will be determined using D-net sampling. We expect that increased sedimentation will reduce the interstitial spaces essential for EPT taxa (Ephemeroptera, Plecoptera, Trichoptera), causing the macroinvertebrate community to shift from EPT taxa towards burrowing taxa less vulnerable to trout predation. Additionally, as an effect of increased sedimentation, we expect a decrease in sinuosity, and stream slope for Caldwell Creek; both of which likely degrade trout habitat. By identifying the mechanisms behind the decline of the brown trout fishery, we hope to determine not only the reasons for past restoration failures but identify where restorative effort should be focused in order to improve the fishery.