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Monday, January 29 • 3:20pm - 3:40pm
SALMONIDS: Effect of Beaver on Brook Trout Habitat in North Shore, Lake Superior Streams

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AUTHORS. Kathryn Renik, Andrew Hafs - Bemidji State University

ABSTRACT. Brook Trout Salvelinus fontinalis are a native species to Minnesota and provide a valued and productive sport fishery to the North Shore streams of Lake Superior. Beaver Castor canadensis dramatically alter the ecosystem they inhabit and are often referred to as a keystone species. Beaver were nearly extirpated from Northeastern Minnesota due to trapping and timber harvest but have since rebounded. Suitable Brook Trout habitat is characterized by cold, spring-fed water with silt-free rocky substrate and abundant cover, all of which Beaver may directly, or indirectly, affect. Data collection occurred on 30 (200 m) stream sections and 10 beaver ponds spanning the North Shore during the summer 2017, with anticipation of data collection occurring in summer 2018 on an additional 30 (200 m) stream sections and 20 beaver ponds. Variables measured included depth, velocity, substrate, temperature, dissolved oxygen, pH, and invertebrates.  Both habitat suitability index (HSI) and bioenergetics models were employed, and through interpolation in geographic information systems (GIS), maps depicting Brook Trout habitat of sampled stream sections were produced. The average HSI and suitable area (m2/100 m2) of each sampled reach were compared to Beaver related activity, including area of water storage above dam, height of dam, and number of dams upstream of sampled sites. Classification regression trees were used to identify significant thresholds in which Beaver activity influenced the amount or quality of Brook Trout habitat. Since the effect of Beaver on Brook Trout varies regionally, this study will provide a simple decision-making flow chart to aid in the development of management strategies pertaining to these two species in North Shore, Lake Superior streams.

Monday January 29, 2018 3:20pm - 3:40pm CST