Distribution and population genetic structure of river‐ and sea‐type sockeye salmon in western North America

• Published in: Ecology of Freshwater Fish
• Main Authors: Gustafson, R. G., Winans, G. A.
• Format: Article in Journal/Newspaper
• Language: English
• Published: Wiley 1999
• Subjects: Ecology; Aquatic Science; Ecology, Evolution, Behavior and Systematics; Sockeye; glacier; Alaska
• Online Access: http://dx.doi.org/10.1111/j.1600-0633.1999.tb00069.x; https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1111%2Fj.1600-0633.1999.tb00069.x; https://onlinelibrary.wiley.com/doi/pdf/10.1111/j.1600-0633.1999.tb00069.x

Abstract– In contrast to the well‐known "lake‐type" sockeye salmon, two additional anadromous life‐history types have been recognized within the species: ‘river‐type’ sockeye salmon whose juveniles spend 1 or 2 years in off‐channel river habitats prior to migrating to sea, and “sea‐type” sockeye salmon that initially rear in similar river habitats yet migrate to sea as underyearlings. Persistent populations of river‐/sea‐type sockeye salmon occur in small numbers throughout the species’range in North America but are usually associated with glacier‐fed rivers. We found published and unpublished records showing that riverine‐spawning sockeye salmon occur in 11 rivers in western Washington, USA, that don't have access to juvenile lake‐rearing habitat. Evidence of persistent spawning was strongest for the Nooksack and Skagit rivers in northern Puget Sound. We analyzed allozyme frequency differentiation in 26 laketype and 12 river‐/sea‐type populations of sockeye salmon in North America, ranging from northern Puget Sound, Washington (including 3 in the Nooksack and Skagit rivers) to northern Southeast Alaska. Across this 2000 km range, river‐/sea‐type sockeye salmon showed very little genetic differentiation between populations, much less than that displayed by the highly divergent lake‐type sockeye salmon. Genetic similarity among river‐/sea‐type sockeye salmon in this study is likely a result of common ancestry and a high level of historical gene flow among river‐/sea‐type sockeye salmon populations.