Sockeye Salmon

A sockeye salmon in ocean coloration.
Photo: Washington Department of Fish and Wildlife

(Oncorhynchus nerka)

Other names: Red Salmon, Blueback Salmon

Sockeye salmon differ from most other species of Pacific salmon, trout, and char by their complete lack of spots. Ocean fish are silver on the sides with a rich blue to blue green coloration on the dorsal surface. Spawning sockeye males and females develop bright red bodies and green heads. Adult fish range from 4-8 pounds in weight and are 18-24 inches long. Male spawning sockeyes develop humped backs like pink salmon. Ocean caught sockeye salmon can often be confused with chum salmon which they closely resemble. Chum salmon have a narrow caudal peduncle (base of the tail) and 19-26 short stout gill rakers on the first (forward-most) gill arch while sockeye salmon have 29-40 long, slender, close-set gill rakers. Sockeye eat smaller prey which accounts for the longer, more closely spaced gill rakers.

 

Distinguishing features of sockeye salmon head and tail. Note the large scales and lack of spots.
Photo: Washington Department of Fish and Wildlife

Abundance, distribution, and natural history

603 total records exist with 82% estimating spawning fish abundance among 26 streams in the park. Sockeye are colonizers of new habitat and glacial outwash plains provide optimal spawning habitat for this species. Sockeye prefer river systems with lakes that provide rearing habitat for fry and juveniles. Most juveniles rear 1-2 years in a lake system. However, juveniles in systems lacking lakes, called “ocean-type” sockeye leave streams soon after hatching for a brief (weeks-months) estuary rearing period. Limited run timing information exists for most park streams. Sockeye enter rivers starting in June or July and spawning individuals are present through November (Fig. 12). Peak spawning occurs during September and October. The most complete run timing data exists for the East Alsek River in the Dry Bay Preserve. A small commercial set gillnet fishery occurs there thus making it a relatively well-studied stream.

 

Female (top) and male (bottom) sockeye salmon in spawning.
Photo: Fisheries and Oceans Canada

Conservation measures and concerns

Glacial habitats that sockeye occupy are rapidly changing and lakes can be relatively ephemeral landscape features due to vegetation colonization and isostatic rebound (absolute increases in ground elevation after glaciers recede and overlying weight is reduced). Reduction in the Vivid Lake spawning population occurred in 1994 when a tributary stream no longer allowed passage for sockeyes into the lake due to rebound. It is possible that other spawning populations (i.e., East Alsek and Bartlett Rivers) within the Park and Preserve may decline as rebound mediated landscape changes affect access to traditional spawning habitat as well as the overall quantity and quality of this habitat.

 

Relative (averaged across records) sockeye salmon run timing for all streams combined (n=495 records) and the East Alsek River (n= 270)