Prespawning movements and spawning distribution of sockeye salmon in an urbanizing Alaskan Lake

Abstract

The efficacy of fish habitat conservation in land planning processes in Alaska is often constrained by the extent of current knowledge of fish distributions and habitat use. In response to requests for information from land and salmon resource management stakeholders regarding Auke Lake sockeye salmon (Oncorhynchus nerka) status and life history, we examined the prespawning movements and spawning distribution of adult sockeye salmon to provide ecological information needed for Auke Lake watershed management. We used radiotelemetry to track the movements of 80 fish in the Auke Lake watershed during 2012. The prespawning distribution of the fish was not random, indicating five spatially and temporally distinct high-use staging areas within the lake. The Auke Lake sockeye salmon population was dominated by stream-spawning fish (98.5%), with minimal lakeshore spawning (1.5%) observed in association with a small intermittent tributary of the lake. The prespawning distribution patterns identified in this study corroborate observations from Auke Lake 20 y ago, indicating consistent habitat use patterns by sockeye salmon in the lake. Telemetry data also indicate 12% of sockeye salmon expired in Auke Lake without spawning and that 14% of stream- spawning fish were preyed upon by black bear (Usrus americanus). The prespawning and spawning behavior by Auke Lake sockeye salmon suggest that discrete lake staging areas and stream spawning beds are important candidate habitats for protection during the land planning process for shoreline development surrounding the lake.