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[Chinook Salmon Ocean and Spawning Stage]

Topics on this page:
General Description
Egg Stage
Alevin Stage
Fry Stage
Smolt Stage
Ocean Stage
Spawning Stage

General Description
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 snout.

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.

Life History
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.

Economic Importance
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

Cultural Importance 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

[Salmon Eggs]

Salmon Eggs

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 redd trapping fish inside. The eggs hatch in about 12 weeks in interior Alaska.

[Chinook Salmon Alevin]

Alevin Stage

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]

Fry Stage

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.

[Chinook Salmon Smolt]

Smolt Stage

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.

[Chinook Salmon Ocean Stage]

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 Spawning Stage]

Spawning Stage

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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