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The Alaskan Sockeye Salmon
Alaska Sockeye Salmon Facts, Information about the
Alaskan "Red", or "Blueback" Pacific Salmon!
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The sockeye salmon (Oncorhynchus nerka), often referred
to as "red" or "blueback" salmon, occurs in the North
Pacific and Arctic oceans and associated freshwater
systems. This species ranges south as far as the Klamath
River in California and northern Hokkaido in Japan, to as
far north as far as Bathurst Inlet in the Canadian Arctic
and the Anadyr River in Siberia. Aboriginal people
considered sockeye salmon to be an important food source and
either ate them fresh or dried them for winter use. Today
sockeye salmon support one of the most important commercial
fisheries on the Pacific coast of North America, are
increasingly sought after in recreational fisheries, and
remain an important mainstay of many subsistence users.
General description:
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 arch. Chum salmon have 19 to 26 short, stout,
smooth rakers.
Immature and prespawning sockeye salmon are elongate,
fusiform, and somewhat laterally compressed. They 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.
Breeding males develop a humped back and elongated, hooked
jaws filled with sharp caniniform 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.
Life history: Sockeye salmon are anadromous: they live in
the sea and enter freshwater systems to spawn. After
hatching, juvenile sockeye salmon may spend up to four years
in fresh water before migrating to sea as silvery smolt
weighing only a few ounces. They grow quickly in the sea,
usually reaching a size of 4 to 8 pounds after one to four
years. Mature sockeye salmon travel thousands of miles from
ocean feeding areas to spawn in the same freshwater system
where they were born. Little is known about the navigation
mechanisms or cues they use on the high seas, although some
evidence suggests that they may be able to use cues from the
earth's magnetic field. Once near their natal freshwater
system, sockeye salmon use olfactory cues to guide them
home. Like all Pacific salmon, sockeye salmon die within a
few weeks after spawning.
Maturing sockeye salmon 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. Freshwater systems with lakes
produce the greatest number of sockeye salmon. Spawning
usually occurs in rivers, streams, and upwelling areas along
lake beaches. 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 as they are extruded.
After each spawning act, the female covers the eggs by
dislodging gravel at the upstream end of the redd with her
tail. A female usually deposits about five batches of eggs
in a redd. Depending upon her size, a female produces from
2,000 to 4,500 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. At this time
they emerge from the gravel as fry and move into rearing
areas. In systems with lakes, juveniles usually spend one to
three years in fresh water before migrating to the ocean in
the spring as smolts. However, in systems without lakes,
many juveniles migrate to the ocean soon after emerging from
the gravel.
Sockeye salmon return to their natal stream to spawn after
spending one to four years in the ocean. Mature sockeye
salmon that have spent only one year in the ocean are called
jacks and are, almost without exception, males. Once in the
ocean, sockeye salmon grow quickly. While returning adults
usually weigh between 4 and 8 pounds, weights in excess of
15 pounds have been reported.
In some areas, populations of sockeye salmon remain in fresh
water all their lives. This landlocked form of sockeye
salmon, called "kokanee," reaches a much smaller maximum
size than the anadromous form and rarely grows to be over 14
inches long.
Food habits: While in fresh water, juvenile sockeye salmon
feed mainly upon zooplankton (such as ostracods,
cladocerans, and copepods), benthic amphipods, and insects.
In the ocean, sockeye salmon continue to feed upon
zooplankton (such as copepods, euphausids, ostracods, and
crustacean larvae), but also prey upon larval and small
adult fishes (such as sand lance), and occasionally squid.
Fisheries: The largest harvest of sockeye salmon in the
world occurs in the Bristol Bay area of southwestern Alaska
where 10 million to more than 30 million sockeye salmon may
be caught each year during a short, intensive fishery
lasting only a few weeks. Relatively large harvests of 1
million to 6 million sockeye salmon are also taken in Cook
Inlet, Prince William Sound, and Chignik Lagoon. All
commercial Pacific salmon fisheries in Alaska are under a
limited entry system which restricts the number of vessels
allowed to participate. Most sockeye salmon are harvested
with gillnets either drifted from a vessel or set with one
end on the shore, some are captured with purse seines, and a
relatively small number are caught with troll gear in the
southeastern portion of the state.
Sockeye salmon are the preferred species for canning due to
the rich orange-red color of their flesh. Today, however,
more than half of the sockeye salmon catch is sold frozen
rather than canned. Canned sockeye salmon is marketed
primarily in the United Kingdom and the United States while
most frozen sockeye salmon is purchased by Japan. Sockeye
salmon roe is also valuable. It is salted and marketed in
Japan.
There is also a growing sport fishery for sockeye salmon
throughout the state. Probably the best known sport fishery
with the greatest participation occurs during the return of
sockeye salmon to the Russian River on the Kenai Peninsula.
Other popular areas include the Kasilof River on the Kenai
Peninsula as well as the various river systems within
Bristol Bay.
Subsistence users harvest sockeye salmon in many areas of
the state. The greatest subsistence harvest of sockeye
salmon probably occurs in the Bristol Bay area where
participants use set gillnets. In other areas of the state,
sockeye salmon may be taken for subsistence use in fish
wheels. Most of the subsistence harvest consists of
prespawning sockeye salmon, but a relatively small number of
post spawning sockeye salmon are also taken. Personal use
fisheries have also been established to make use of any
sockeye salmon surplus to spawning needs, subsistence uses,
and commercial and sport harvests. Personal use fisheries
have occurred in Bristol Bay, where participants use set
gillnets, as well as in Cook Inlet and Prince William Sound,
where participants also use dip nets.
While most sockeye salmon production in Alaska results from
the spawning of wild populations, some runs have been
developed or enhanced through human effort. Although
artificial propagation of sockeye salmon has proven
difficult, notable success has been achieved at
state-maintained hatcheries located on the upper Copper
River in Prince William Sound and the Kasilof River on the
Kenai Peninsula. A fish ladder installed on the Fraser River
on Kodiak Island has also served to enhance sockeye salmon
returns.
Text: Commercial Fisheries Management and Development Staff
Illustration: Ashley Dean
Revised and reprinted 1994
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