Chinook salmon
From Freepedia
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| Oncorhynchus tshawytscha (Walbaum, 1792) |
The Chinook salmon (Oncorhynchus tshawytscha) (derived from Russian чавыча), is a species of anadromous fish in the salmon family. It is a Pacific Ocean salmon and is variously known as the King salmon, tyee salmon, Columbia River salmon, black salmon, chub salmon, hook bill salmon, winter salmon and blackmouth.
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Appearance
The Chinook salmon is blue-green on the back and top of the head with silvery sides and white ventral surfaces. It has black spots on the upper half of its body and the mouth is a dark gray. Adult fish average 33 to 36 inches (840 to 910 mm), but may be up to 58 inches (1.47 metres) in length; they average 10 to 50 pounds (5 to 25 kg), but may reach 130 pounds (50 kg).
Reproduction
Chinook salmon may spend between one to eight years in the ocean before returning to their home rivers to spawn, though the average is three to four years. Chinook prefer larger and deeper water to spawn in than other species of salmon and can be found on the spawning redds (nests) from September through to December. Fry and parr (young fish) usually stay in freshwater from twelve to eighteen months before travelling downstream to estuaries, where they remain as smolts for several months.
Range
Chinook salmon range from Santa Barbara in California up to Chukchi Sea north of the Bering Strait in Alaska, and the whole Pacific coast in between. It is also found in Kamchatka and the Kuril Islands in Russia. The most significant spawning runs are in the Columbia River, Rogue River, and Puget Sound. Within this range there are probably more than 1,000 spawning populations, yet the species is the least abundant salmon in North America.
The Yukon River has the longest freshwater migration route of any salmon, over 3,000 kilometres from its mouth in the Bering Sea to spawning grounds upstream of Whitehorse, Yukon. A fish ladder has been constructed around the Schwatka Lake hydroelectric dam in Whitehorse to allow the passage of Chinook salmon.
Ecology
Chinook salmon need five things to survive:
- food,
- spawning habitat,
- ocean habitat,
- clean, oxygenated water, and
- other salmon
(Christie, referring to salmon in the Puget Sound area).
First, salmon need to be able to have ample food resources, such as: planktonic diatoms, copepods, kelps, seaweeds, jellyfish, and sea stars. As with all Salmonid species, Chinook feed on insects, amphipods, and other crustaceans while young, and primarily on other fish when older. Young salmon feed in streambeds for a short period of time until they are strong enough to journey out into the ocean and acquire more food. Once they spend a couple of years in the ocean, adult salmon grow large enough to escape most predators and return to their original streambeds to mate.
Second, in order for salmon to be able to spawn, they must have a healthy habitat that is sheltered by eelgrass and other seaweeds. These sea plants camouflage eggs so that they are protected from predators. Also, they help shelter infant salmon so that they have the chance to eat and grow before making the journey to the ocean to join other juveniles.
Third, with regards to ocean habitat, it is essential that anadromous (freshwater-breeding) salmon migrate from stream beds to the oceans and have the ability to grow into adult fish. This is because these adult fish acquire the strength that is needed to travel back upstream, escape predators, and reproduce before dying. In fact, in his book King of Fish, David Montgomery writes that, "The reserves of fish at sea are important to restocking rivers disturbed by natural catastrophes". Thus, it is vitally important that fish are able to reach the oceans (without man-made obstructions like dams) so that they can grow into healthy adult fish that will further populate the species.
Fourth, it is important that the bodies of water are clean and oxygenated. One sign of high productivity/growth rate in the oceans are the levels of algae. Increased levels of algae lead to higher levels of carbon dioxide in the water which is transferred into living organisms, fostering growth of underwater plants and small organisms, which salmon eat (Klinger). Also, algae can contribute in filtering the water from high levels of toxins and pollutants. Thus, it is essential that algaes and other water filtering agents are not destroyed in the oceans because they contribute to the overall well-being of the ocean food chain.
Finally, salmon need other salmon to survive so that they can reproduce and pass on their genes in the wild. With the species being endangered, it is important that precautions are taken to ensure that salmon are not being overfished. If there are too few fish left because of harmful fishing practices, it makes it more difficult for salmon to regenerate a more abundant population that will continue into the future.
When one of these five variables is destroyed or unserviceable, it leads to a decline in salmon stock. One Seattle Times article states, "Pacific salmon have disappeared from 40 percent of their historic range outside Alaska," and concludes that it is imperative that people realize the needs of salmon and try not to contribute to destructive practices that harm salmon runs (Cameron).
Commerce
Chinook salmon are highly valued, despite their scarcity relative to other Pacific salmon along most of the Pacific coast.
Chinooks are sometimes called "King Salmon" because many consider them to be the best tasting of the salmon species. Those from the Copper River in Alaska are particularly known for their color, flavor, firm texture, and high Omega-3 oil content.
The species was described, and enthusiastically eaten, by the Lewis and Clark expedition.
References
- Cameron, Mindy. Salmon Return; A Public Conversation About the Future of a Northwest Icon. The Seattle Times. [Seattle, WA]. 18 August 2002.
- Christie, Patrick. Lecture. 22 April 2005. Vashon-Maury Islands Case Study: Incompatible Desires? Growth and Maintaining Salmon Populations in Puget Sound. University of Washington; Seattle, WA.
- Klinger, Terrie. Lecture. 15 April 2005. What Defines the Pacific Northwest Marine Realm Ecologically and Geographically? University of Washington; Seattle, WA.
- Montgomery, David. King of Fish: The Thousand-Year Run of Salmon. Boulder, CO: Westview Press, 2003.
External links
- Fish Passage Center, monitoring salmon spawning and migration
