Projects and partners

Abnormally high piscicolid leech infestations on Northern Pike in Interior Alaska

Collaborators: Kevin Fraley (Wildlife Conservation Society), Morag Clinton (Sitka Sound Science Center), Taylor Cubbage (Alaska Department of Fish and Game), and Joe Spencer (Alaska Department of Fish and Game and University of Alaska Fairbanks)

Fragmentation of freshwater habitat negatively impacts riverine fish communities and habitat restorations—which often include retrofitting/replacing culverts—are conducted widely to restore stream connectivity. Monitoring fish assemblages in impaired habitats prior to restorations is necessary to justify the significant costs required for restoration work and to demonstrate the efficacy of habitat improvements. To characterize the fish community prior to an ongoing restoration of Cripple Creek in Interior Alaska, fish catch data from 2018–2020 were analyzed for abundance, distribution, and size trends with a focus on the two most prevalent species, Lake Chub (Couesius plumbeus), and Longnose Sucker (Catostomus catostomus). We found that the weekly mean length of Lake Chub increased during the 2020 summer, suggesting that fish are using the Cripple Creek drainage for rearing. Mean fish length was greater, and abundance was consistently lower in an upper section of the creek compared to the lowest section, supporting the idea that unrestored culverts limit fish passage, especially for smaller fish with weaker swimming abilities. Additionally, we recorded the first juvenile Chinook Salmon (Oncorhynchus tshawytscha) observed in the Cripple Creek drainage. These findings provide justification for the ongoing Cripple Creek restoration project and suggest that fish passage improvements are necessary in Interior Alaska. We are actively involved in ongoing biomonitoring, post-restoration evaluation, and future project planning.