Salmon, Sockeye (Oncorhynchus nerka)

A member of the Salmonidae family, sockeye leave the ocean to spawn in freshwater, as do other Pacific salmon, but they enter only those rivers having lakes at their headwaters. The erection of dams and the alteration of habitat, however, as well as commercial overfishing and other factors, have caused an overall decline in sockeye stocks and the loss of some specific runs.

Identification

The sockeye is the slimmest and most streamlined of Pacific salmon, particularly immature and pre-spawning fish, which are elongate and somewhat laterally compressed. The sockeye is metallic green-blue on the back and the top of the head, iridescent silver on the sides, and white or silvery on the belly. Some fine black speckling may occur on the back, but large spots are absent.

Breeding males develop humped backs and elongated, hooked jaws filled with sharp, enlarged teeth. Both sexes turn brilliant to dark red on their backs and sides, pale to olive green on their heads and upper jaws, and white on their lower jaws. The totally red body distinguishes the sockeye from the otherwise similar chum salmon, and the lack of large, distinct spots distinguishes it from the remaining three Pacific salmon of North America.

Size

Adult sockeye usually weigh between 4 and 8 pounds. The all-tackle world record is an Alaskan fish that weighed 15 pounds, 3 ounces.

Life history/Behavior

Sockeye salmon return to their natal stream to spawn after spending 1 to 4 years in the ocean. They enter freshwater systems from the ocean during the summer months or the fall, some having traveled thousands of miles. Most populations show little variation in their arrival time on the spawning grounds from year to year.

Food and feeding habits

In the ocean, sockeye salmon feed on plankton, plus on crustacean larva, on larval and small adult fish, and occasionally on squid.

Other Names

sockeye, red salmon, blue back salmon, big redfish; French: saumon nerka; Japanese: beni-zake, himemasu. The landlocked form is called kokanee salmon, Kennerly’s salmon, kokanee, landlocked sockeye, kickininee, little redfish, silver trout; French: kokani.

Distribution

The sockeye salmon is native to the northern Pacific Ocean and its tributaries; in North America it occurs from the Sacramento River, California, to Point Hope, Alaska.