Sockeye Salmon

Appearance

Sockeye salmon can be distinguished from Chinook, coho, and pink salmon by the lack of large, black spots and from chum salmon by the number and shape of gill rakers on the first gill arch. Sockeye salmon have 28 to 40 long, slender, rough or serrated closely set rakers on the first gill arch, while chum salmon have 19 to 26 short, stout, smooth rakers. Immature and prespawning sockeye salmon are metallic green-blue on the back and 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.Juveniles, while in fresh water, have the same general coloration as immature sockeye salmon in the ocean but are less iridescent. Juveniles also have dark, oval parr marks on their sides. These parr marks are short (less than the diameter of the eye) and rarely extend below the lateral line. Upon maturing in fresh water, breeding males develop a humped back and elongated, hooked jaws filled with sharp teeth. Both sexes turn brilliant to dark red on the back and sides, pale to olive-green on the head and upper jaw, and white on the lower jaw.

Maximum Size

Sockeye salmon reach up to 2.8 feet (85 cm) in length, and the average weight of the fish is about 8 pounds (3.6 kg).

Growth Rate

Slow compared to other Pacific salmon species.

Geographic Range

Sockeye salmon commonly spawn and rear in freshwaters from the Columbia River and its tributaries north and west to the Kuskokwim River in Alaska. After migrating from the inland habitats, sockeye rear and mature in the oceanic waters of the North Pacific and Arctic. This species ranges south as far as the Klamath River in California and northern Hokkaido in Japan, to as far north as Bathurst Inlet in the Canadian Arctic and the Anadyr River in Siberia.

Habitat

Sockeye inhabit streams, rivers, lakes, estuaries, and marine environments.

Life Span

Sockeye salmon typically mature at an age of 5 years and return to spawn in their natal freshwater habitat; age 4 and 6 fish are common with fish maturing at 2, 3, 7 or 8 years occasionally. Salmon die within a few weeks after spawning.

Food

While in fresh water, juvenile sockeye salmon feed mainly upon zooplankton (tiny floating animals), benthic amphipods (small, shrimp-like crustaceans), and insects. In the ocean, sockeye salmon continue to feed upon zooplankton but also prey upon larval and small adult fishes (such as sand lance), and occasionally squid.

Reaches Reproductive Maturity

Sockeye salmon typically mature and return to freshwater after 2 or 3 years at sea, but they occasionally stay at sea for 1,4, or 5 years. Mature sockeye salmon that have spent only 1 year in the ocean are almost always males, which are called jacks.

Reproduction

Most* sockeye salmon are anadromous, meaning they migrate from a marine environment into fresh water streams and rivers or lakes of their birth in order to mate. The female selects the spawning site, digs a nest (redd) with her tail, and deposits eggs in the downstream portion of the redd as one or more males swim beside her and fertilize the eggs. After each spawning act, the female covers the eggs by dislodging gravel at the upstream end of the redd with her tail. A female produces from 2,000 to 4,500 eggs depending upon her size and usually deposits about five batches of eggs. Eggs hatch during the winter, and the young sac-fry, or alevins, remain in the gravel, living off the material stored in their yolk sacs until early spring when they emerge as fry and move into rearing areas. Typically, juveniles spend 1 to 3 years in freshwater before migrating to the ocean in the spring as smolts. In some systems, juveniles migrate to the ocean soon after emerging from the gravel. Like all Pacific salmon, sockeye salmon die within a few weeks after spawning.*Some sockeye salmon are non-anadromous and spend their entire lives in freshwater. Non-anadromous Oncorhynchus nerka in the Pacific Northwest are known as "kokanee." Taxonomically, kokanee and sockeye salmon do not differ, and they are occasionally observed on the spawning grounds together. Kokanee reach a smaller maximum size than the anadromous form, rarely exceeding 14 inches (35.5 cm) long.

Spawning

Sockeye salmon typically spawn in the summer or fall, doing so in or near lakes, where the juveniles stay for 1 to 3 years before migrating to sea.

Migrations

Sockeye salmon are anadromous fish that migrate from the ocean to spawn in fresh water. Mature sockeye salmon travel thousands of miles from ocean feeding areas to spawn in the same freshwater system where they were born. Maturing sockeye salmon typically return to freshwater systems from the ocean during the summer months, and most populations show little variation in their arrival time on the spawning grounds from year to year.

Predators

Predators of juveniles include fish (including other salmon) and birds. Predators of adults in the ocean include sharks, lampreys, and marine mammals, and bears and occasionally wolves and eagles in fresh water.

Information courtesy of NOAA.


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