Instream Habitat Restoration and Stream Temperature Reduction in a Whirling Disease-Positive Spring Creek in the Blackfoot River Basin, Montana

Abstract

Anthropogenic warming of stream temperature and the presence of exotic diseases such as whirling disease are both contemporary threats to coldwater salmonids across western North America. We examined stream temperature reduction over a 15-year prerestoration and postrestoration period and the severity of Myxobolus cerebralis infection (agent of whirling disease) over a 7-year prerestoration and postrestoration period in Kleinschmidt Creek, a fully reconstructed spring creek in the Blackfoot River basin of western Montana. Stream restoration increased channel length by 36% and reduced the wetted surface area by 69% by narrowing and renaturalizing the channel. Following channel restoration, average maximum daily summer stream temperatures decreased from 15.7°C to 12.5°C, average daily temperature decreased from 11.2°C to 10.0°C, and the range of daily temperatures narrowed by 3.3°C. Despite large changes in channel morphology and reductions in summer stream temperature, the prevalence and severity of M. cerebralis infection for hatchery Rainbow Trout Oncorhynchus mykiss remained high (98–100% test fish with grade > 3 infection) versus minimal for hatchery Brown Trout Salmo trutta (2% of test fish with grade-1 infection). This study shows channel renaturalization can reduce summer stream temperatures in small low-elevation, groundwater-dominated streams in the Blackfoot basin to levels more suitable to native trout. However, because of continuous high infections associated with groundwater-dominated systems, the restoration of Kleinschmidt Creek favors brown trout Salmo trutta given their innate resistance to the parasite and the higher relative susceptibility of other salmonids.

Received February 3, 2014; accepted May 3, 2014

ACKNOWLEDGMENTS

Montana Department of Transportation, Montana Fish, Wildlife and Parks Future Fisheries Program, the Big Blackfoot Chapter of Trout Unlimited, Northwestern Energy, and the U. S. Fish and Wildlife Service Partners for Fish and Wildlife all helped fund the restoration of Kleinschmidt Creek. Land and Water Consulting oversaw most of the design and implementation. Streamworks performed most of the channel reconstruction. Landowners Jon Krutar, Ross Friede, and Tom Rue allowed the work and provided cost-share and in-kind support. Montana Fish, Wildlife and Parks staff including Mike Davidson, Winston Morton, Jody Hupka, Dick Vincent, Linnaea Schroeer, Ryen Neudecker, and Nick DeCesare all assisted in the data collection and analyses. Ryen Neudecker, Lisa Eby, Katelyn Driscoll, and three anonymous reviewers provided helpful feedback and improved the quality of the manuscript. Any use of trade, firm, or product names is for descriptive purposes only and does not imply endorsement by the U.S. Government.