Dan Dauwalter and Kurt Fesenmyer, Trout Unlimited - Science
The Goose Creek subbasin in the Upper Snake River Basin has a diverse native fish assemblage that reflects the presence of rare non-game species and peripheral populations of Yellowstone Cutthroat Trout.
This assessment examined linkages between native fishes and their habitat in the Goose Creek subbasin with several key findings: 1) fish diversity is linked to habitat diversity, and habitat diversity is linked to stream condition;2) various elements of habitat complexity are important to several native fishes at different spatial scales; and 3) land management focused on riparian and stream health is important in maintaining the habitat complexity important to fish community diversity and sensitive fish species that are rare in the Upper Snake River Basin.
Using data from fish and habitat surveys throughout the Goose Creek watershed, we found that diversity in cover (e.g., large wood, undercut bank), substrates (e.g., boulders, gravel), water velocity, and water depths were all important in explaining diversity in the fish community across sample sites
The distribution of Northern Leatherside Chub in Goose Creek is influenced by streamflow complexity, and that streamflow complexity is typically higher when active or abandoned beaver dams are present. This suggests beaver reintroductions or beaver dam analogs should be evaluated as a stream restoration practice for Northern Leatherside Chub conservation in an adaptive management framework.
Northern Leatherside Chub also select microhabitats with overhead cover from mature woody and herbaceous riparian vegetation and streamflow complexity influenced by riffle-pool morphology, overhanging bank vegetation, and beaver dams. Maintaining riparian health standards should create Northern Leatherside Chub habitats used at small spatial scales to presumably benefit population dynamics that facilitate persistence
Yellowstone Cutthroat Trout abundance is limited by both Brook Trout and habitat complexity at the subspecies’ range periphery, and that Brook Trout negatively influences and instream cover diversity positively influences body condition of age-0 Cutthroat Trout. The negative interaction between Brook Trout and Cutthroat Trout early in life has been shown previously and emphasizes removal of Brook Trout as a cutthroat trout conservation action. However, this study also suggests that conserving or restoring habitat complexity should be more widely considered and evaluated as a complementary action that could promote coexistence of the two species