The migration and spawning distribution of sockeye salmon within Lake Clark, Alaska

Abstract

Recent declines in the number of sockeye salmon Onchorynchus nerka returning to Lake Clark, Alaska have caused economic hardship in the region and raised resource concerns among local subsistence users and Federal managers. A lack of information regarding the distribution of spawning habitats in the glacially turbid Lake Clark watershed instigated this research. Radio telemetry was used to 1) determine the in-lake movement patterns of adult sockeye salmon and 2) identify sockeye salmon spawning locations. Sockeye salmon were radio tagged at they entered Lake Clark and tracked to spawning locations. After entering Lake Clark, sockeye salmon usually migrated to a region of the lake that was within 15 km of their spawning location. Tagged fish migrated faster and more directly to spawning locations in tributary rivers and lakes than to Lake Clark beaches. Thirty three spawning locations were identified in the Lake Clark watershed including 18 new spawning locations compared to previous scientific research and ten compared to traditional local knowledge. Most radio tagged sockeye salmon (65%) returned to spawning locations in glacially turbid waters and most spawning locations (75%) were adjacent to privately owned lands. Proactive measures should be taken to conserve both migration corridors and spawning habitats.