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The Chinook salmon, Oncorhynchus tshawytscha, is Alaska's state fish. It is also the
largest of the Pacific salmon. The largest Chinook salmon ever documented, a 126 lb fish, was
caught in a fish trap near Petersburg, Alaska in 1949. A 97 lb Chinook was caught on sport tackle near
Admiralty Island in south east Alaska.
Other common names for this fish are king or red salmon. In the ocean, Chinook have
blueish-green backs and silver sides, with irregular black spotting on the back,
dorsal fin and both lobes of the tail. Spawning fish in
interior Alaska rivers are bright red and males develop a hooked
Range And Abundance
Spawning populations of Chinook salmon are found all the way from the Ventura River in
southern California north to Point Hope, Alaska. The Yukon and Nushagak Rivers in Alaska,
have the largest runs of Chinook salmon in the world.
Chinook salmon spawn from July to mid-August in the Yukon River drainage. alevin remain in the gravel until the yolk sac has been absorbed,
usually about 2-3 weeks after hatching,then they work their way up through the gravel and
become free-swimming, feeding fry.
Chinook salmon fry stay in fresh water for a year in the Yukon River drainage before migrating to
estuaries and tidal creeks. They stay close to shore for
several months then gradually move into deeper,saltier water. Alaskan Chinook salmon can stay
at sea for 2 to 5 years.
The Chinook salmon's large size and high-quality flesh makes it one of Alaska's most valuable
commercial fisheries. Yukon River commercial fishermen caught over * 45,000 Chinook
salmon in 2006. Chinook salmon are also one of Alaska's most
prized sport fish. Anglers in the Kenai Peninsula alone spend over 40 million dollars annually,
much of it in pursuit of Chinook salmon.
* Figures provided by ADF&G Alaska 2006 Special Publication No. 07.01
Chinook salmon are probably the most important subsistence fish for native people living along
Interior rivers. Over * 56,000 Chinook salmon were harvested among the 40 rural communities
along the Yukon River in 1997. Chinook salmon are harvested with gill nets, beach seines and fish wheels and are eaten fresh, smoked, and canned.
* Figures provided by ADF&G Alaska Subsistence Fisheries 2003 Annual Report
The number of eggs produced by a female Chinook can range from 2,000 to over 17,000!
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 dangerous as it can smother eggs or cover the
trapping fish inside. The eggs hatch in about 12 weeks in interior Alaska.
A newly hatched salmon is called an alevin. At this stage, it looks like a thread with eyes and an
enormous yolk sack which provides all nutrition for the fish in the first weeks of its life. Alevin
remain in the redd until the yolk sac is absorbed. At this point, they work their way up through
the gravel and become free-swimming, feeding fry.
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 an
alevin's primary predators.
Chinook salmon fry stay in fresh water for a year in the Yukon River
drainage. The young fish initially live in quiet pools. Their parr marks (bars and spots along
their sides) help them hide among the cover provided by rocks, stumps, undercut banks and overhanging
vegetation. As Chinook salmon fry grow larger, they move out into more open, faster moving water. During
their fresh water residence, Chinook salmon fry feed chiefly on terrestrial insects, small
crustaceans, or anything available to them, although they do not
appear to eat other fish at this time.
Many physical changes occur in a young salmon to help it make the transition from a freshwater
to saltwater existence. This process is called smolting. As the
time for migration to the sea approaches, the Chinook salmon replaces its parr marks, a pattern of
vertical bars and spots useful for camouflaging the fry in fresh water, with the dark back and light
belly coloration used by fish living in open water. They seek deeper water, avoid light, and their gills and kidneys begin to
change so that they can process salt water.
The young fish remain in estuaries and tidal creeks for several months
feeding on small fish,insects, crustaceans and mollusks.
They gradually move into deeper, saltier water, but remain near shore.
Ocean Stage Adult
Alaskan Chinook salmon can stay at sea for 1 to 5 years. In the Yukon River, 6 year old fish
dominate the returning runs. During their ocean existence, chinook salmon primarily eat fish
along with amphipods, mollusks, crab
larvae and squid.
Some Chinook salmon remain close to shore during their ocean residence, but most undertake
extensive migrations. Fish from Alaskan streams enter the Gulf of Alaska and move extensively
across the northern Pacific. In the spring of the year, Chinook salmon scatter across the northern
Pacific and the Bering Sea. In the summer their numbers increase in the area of the Aleutian
Islands and in the western Gulf of Alaska.
Chinook salmon reach sexual maturity between 3 and 7 years of age. In the Yukon
River 6 year old fish dominate the returning runs.
Chinook salmon begin entering the Yukon River in early June. Fish migrating to Canada reach
the border by mid to late July. Spawning takes place from July to mid-August in the
Yukon drainage. The fish select spawning sites with high water flow through the gravel which
will provide plenty of oxygen for their eggs.
Once a female salmon selects a spawning site, 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 uses the same tail movements to completely cover the eggs with gravel. Over
several days, she will lay several more pockets of eggs like this in a line upstream.
Text by USFWS staff
Graphics used by permission of Harry Heine
Last modified 24, February, 2009
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