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The sockeye salmon, Oncorhynchus nerka, is the only Pacific salmon where the fry rear almost exclusively in lakes. In the ocean stage, sockeyes
are greenish blue on the top of the head and back, silvery on the sides and white to silver on the
belly. At spawning, the head and caudal fin become bright
green and the body turns brilliant scarlet giving the sockeye its other common name, “red salmon”.
Sockeyes can reach a length of about 34 inches and a weight of about 15 pounds. Most fish are around
26 inches in length, and 7 to 11 pounds.
Range And Abundance
The sockeye salmon ranges from the Klamath River in Oregon to Point Hope in northwestern Alaska.
Sockeyes have been caught in the Yukon River as far up as Rampart. On the Asian side of the
Pacific Ocean, sockeyes are also found from the Anadyr River in Siberia south to Hokkaido, Japan.
The largest sockeye populations are in the Fraser River system in Canada, and in the Kvichak,
Naknek, Ugashik, Egegik, and Nushagak Rivers that flow into Alaska’s Bristol Bay. In good years,
these runs have tens of millions of fish.
Adult sockeyes return to spawn between July and October. Spawning occurs most commonly in streams
that connect to lakes. The female deposits between 2,500 to 4,300 eggs in 3 to 5 redds that are fertilized by the male. Spawning can take place over three to five days.
Hatching occurs from mid-winter to early spring, and fry emerge from the gravel between April and
June. Most of the fry swim to a lake and reside there for one to two – or rarely three or four years
before going to sea. Smolts initially stay close to the shore and feed on
insects and plankton. Once they move
offshore, their diet turns mainly to amphipods, copepods, squid, and some
fish. Most sockeyes stay at sea for two years, returning to spawn in their fourth year, but some may
be five or six.
Sockeye salmon are the most economically important salmon in Alaska. More pink and chum salmon are
caught, but sockeyes are a higher quality fish and sell for a much higher price. There is also a
sockeye sport fishery.
Sockeyes are an important fish for Alaska Natives who are commercial and subsistence fishermen.
Most fish are caught using gill nets and beach seines.
Sockeye salmon lay between 2,500 – 4,300 eggs. Five hundred to one thousand eggs are
deposited in each of three to five gravel nests, called redds, made by the female.
Hatching can occur in six to nine weeks or up to five months depending on water
temperature. Most eggs hatch from mid-winter to early spring.
Up to 85% of the eggs can be lost before hatching. Low oxygen levels, freezing,
water pollution, and predation by fish, insects and birds are all threats at this
stage. Excess sediment in the water is also extremely detrimental as it can smother
the fragile eggs.
Alevin must have cold, clear, oxygen-rich water to remain healthy. Excessive
sediment in the water is one of the greatest dangers to salmon at this stage.
It can smother newly-hatched fish or cover the top of the redd, trapping the
alevin inside. Aquatic insects and other fish are the primary predators of
After emerging from the stream gravel, the fry swim upstream or downstream to a lake.
They live there for one to two (or rarely three or four years) before migrating to the sea.
Initially, the fry stay in the shallow water near the lake shore, but gradually move into
deeper water. While in the lakes, they feed on aquatic insects and plankton.
Many physical changes occur in a young salmon to help it make the transition from freshwater
to a saltwater existence. It turns silvery to match its new open water environment, and the
gills and kidneys change so that they can process salt water. Peak migration from lakes to
the ocean occurs in June in Bristol Bay. Once in the sea, sockeye salmon smolts stay close
to shore initially, but gradually move into deeper water. Their food consists of zooplankton,
insects and small fish.
Ocean Stage Adult
Most Alaskan sockeye salmon spend two or three years in the ocean. Amphipods, copepods, and squid
become a large part of the diet as the fish mature.
Sockeye salmon from south of the Alaska Peninsula move into and follow a counter-clockwise current
called the Alaska Gyre in the Gulf of Alaska. Sockeyes from Bristol Bay move west along the north
side of the Alaska Peninsula, then turn south through Aleutian passes into the Gulf. Most sockeyes
spend the summer in a broad band across the western Pacific Ocean south of the Aleutian chain which
is an important feeding area. The following winter, the fish split into immature populations and
those that will mature and spawn the following year. Younger fish head south into the Gulf of Alaska
again, and maturing fish stay north of 50 degrees north latitude.
The majority of Alaskan sockeye salmon return to spawn at four years old, but some may be five or six.
Spawning occurs between July and October almost exclusively in lakes or streams that connect to lakes.
The male salmon guards the female from other males while she rapidly pumps her tail to wash out a
depression in the stream gravels. As she deposits her eggs, they are fertilized by the male. The female
salmon then moves directly upstream and uses the same tail movements to dig again. In this way, the eggs
are covered, and a new redd is created. She will create three to five redds over a three to five day period.
Text by USFWS staff
Graphics used by permission of Harry Heine
Last modified 4, March, 2009
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