Southeast Alaska Salmon Life History Strategies and Habitats That Provide Species Resilience

Some salmon stocks utilizing Southeast Alaska’s streams exhibit an age-0 ocean-type life history strategy that may help them maintain resilience.  Chinook salmon in the Situk River, near Yakutat are unique because they are the only known stock in Alaska that migrates to sea at primarily at age 0.  Chinook juveniles migrated downstream in the Situk in two phases: a dispersal in spring after emergence followed by a mid-summer migration.  Sockeye salmon in the Situk River also exhibited the age 0, ocean-type life history strategy including two distinct patterns in their migration that allowed them to exploit the higher productivity of estuarine habitats.  The Taku River, a transboundary river near Juneau, also has age-0 sockeye consisting of two groups that moved downstream at different times.  Coho salmon from several systems in Southeast Alaska also appear to be using the age-0 life history strategy, but differ from Chinook and sockeye in that many of these coho migrate back into freshwater to overwinter before migrating to the ocean as typical smolts.  Consequently, coho fry from a stream may enter the estuarine environment, rear there for awhile, and then migrate back upstream to overwinter and smolt from a non-natal stream.  Estuarine and overwintering habitats need particular protection to maintain these unique life history strategies, species resilience and aid in the recovery of depressed stocks.