Amphibian Persistence in Wilderness Lakes: A Case Study for Managers

David S. Pilliod and Charles R. Peterson Department of Biological Sciences, Idaho State University, Pocatello

The goal of this paper is to provide recommendations for developing studies that adequately evaluate recreational fisheries threats to amphibian persistence in wilderness lakes. These recommendations are based on five years of amphibian and fish surveys in high-elevation lakes in the Frank Church - River of No Return Wilderness, Idaho. Specifically, we will address the following questions. Where and how many sites should be surveyed? How often do sites need to be surveyed? What information should be collected at each site and how should the resulting data be analyzed and interpreted? And finally, what are the "costs" and "benefits" of implementing different management actions? We recommend that resources be put into conducting comprehensive surveys over smaller areas (e.g., specific drainages or basins), rather than sub-sampling lakes over larger areas (e.g., an entire wilderness area). Although this may reduce regional generality, it is critical for assessing threats to amphibian persistence at the landscape scale. Surveys need to be conducted multiple times per year, and ideally over multiple years to avoid false conclusions based on natural population fluctuations and survey variability. To determine whether trout may be threatening amphibian persistence, it is important to evaluate amphibian populations not only as present or absent, but include relative abundance, breeding, and recruitment. We address the differences between these data and discuss how they influence our perception of the problem. Lastly, we provide a framework for evaluating the effects of different management actions on native amphibians and recreational fisheries. Our preliminary work indicates that relatively moderate changes for recreation may result in significantly decreasing the probability of local extinction of native amphibians in wilderness areas.

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