Aquatic Sciences Meeting, Albuquerque 2001

CS14 Fish and Fisheries: Environmental Quality and Ecology

Date: Thursday, February 15, 2001, Time: 4:30:00 PM

Location: Sandia/Santa Ana

Hoffman, R, L, Oregon State University, Corvallis OR, USA, robert.hoffman@orst.edu

Larson, G, L, U.S. Geological Survey, Corvallis OR, USA, Gary_L._Larson@usgs.gov

RESPONSE OF LARVAL SALAMANDERS TO THE REMOVAL OF NONNATIVE FISH FROM MOUNTAIN LAKES

Introductions of fishes to naturally fishless mountain lakes have been identified as negatively affecting amphibians. Introduced fish can decrease amphibian abundance and alter larval behavior. In 1996, we began a project in Mount Rainier National Park, Washington, USA, with the objective to assess salamander population response to fish removal. In one lake prior to fish removal, larvae were restricted to nearshore habitats and active primarily at night. After fish removal, larvae increased in abundance in offshore habitats and increased their diel activity. Egg mass counts increased from 3-15 per 150 m pre-fish removal to 26-107 per 150 m post-fish removal. In a second lake, the number of larvae of two salamander species has steadily increased since fish removal. These responses have also been observed in a fish removal lake in North Cascades National Park Service Complex, Washington, USA. These changes in abundance, location, and diel pattern of larvae represent the ecological release of larvae from the threat of predation by introduced fish, indicating that larval behavior becomes less restricted and secretive after fish are removed from mountain lakes.

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Aquatic Sciences Meeting, Albuquerque 2001

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