New Sampling Design Reveals Hotspots for Brook Trout Recruitment in Catoctin Mountain Park
Nathaniel Hitt- Aquatic Ecologist, U.S. Geological Survey, Leetown Science Center
Catoctin Mountain Park (CATO) provides some of the last, best habitat for native brook trout in the region. However, surveys by the Maryland Department of Natural Resources in CATO indicate declining brook trout numbers over the last decade. We sampled brook trout using a spatially-extensive sampling design throughout Owens Creek watershed in 2015 (single-pass backpack electrofishing in 100m blocknetted reaches) to evaluate effects of stream temperature, physical habitat, and brown trout abundance. Abundances of juvenile brook trout (young-of- year, YOY) were highly variable among locations, suggesting metapopulation dynamics such that some locations may provide important sources of colonists for connected streams. High-density YOY locations supported colder stream temperatures and smaller fish, suggesting thermally-limited growth rates and/or competitive interactions among individuals. We describe the implications for climate change analysis, and we highlight the importance of key locations for conservation of brook trout in CATO.
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