Chinook salmon

The chinook salmon, Oncorhynchus tshawytscha (derived from Russian чавыча, which in turn comes from a common name used among natives in Alaska and Siberia), is an anadromous fish that is the largest species 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, Spring Salmon, Quinnat Salmon and blackmouth. Chinook salmon are highly valued, due in part to their relative scarcity compared to other salmon along most of the Pacific coast.

Contents 1 Physical description 2 Lifecycle 3 Range and habitat 3.1 Introductions 3.2 Management 4 Chinook in Culture and Commerce 5 See also 6 References 7 External links

Physical description

The chinook is blue-green or purple on the back and top of the head with silvery sides and white ventral surfaces. It has black spots on its tail and the upper half of its body. Its mouth is often dark purple. Adult fish range in size from 33 to 36 in (840 to 910 mm) but may be up to 58 inches (1,500 mm) in length; they average 10 to 50 pounds (4.5 to 23 kg) but may reach 130 pounds (59 kg). The current sport-caught World Record is 97.25 pounds (44 kg) and was caught in May 1985 by Les Anderson in the Kenai River (Kenai, Alaska). The commercial catch world record is 126 pounds (57 kg) caught near Rivers Inlet British Columbia in the late 1970s.^[1]

Lifecycle

Chinook salmon may spend 1 to 8 years in the ocean (averaging from 3 to 4 years)^[2] before returning to their home rivers to spawn. Chinook spawn in larger and deeper waters than other salmon species and can be found on the spawning redds (nests) from September through to December. After laying eggs, females guard the redd from 4 to 25 days before dying, while males seek additional mates. Chinook salmon eggs hatch, depending upon water temperature, 90 to 150 days after deposition. Egg deposits are timed to ensure that young salmon fry emerge during an appropriate season for survival and growth. Fry and parr (young fish) usually stay in freshwater 12 to 18 months before traveling downstream to estuaries, where they remain as smolts for several months. Some chinooks return to the fresh water one or two years earlier than their counterparts, and are referred to as "Jack" salmon. "Jack" salmon can be half the size of an adult chinook salmon, and are usually released by sportsmen but kept by commercial fishermen.^{[citation needed]}

Range and habitat

Chinook salmon range from San Francisco Bay in California to north of the Bering Strait in Alaska, and the arctic waters of Canada and Russia (the Chukchi Sea). Populations occur in Asia as far south as the islands of Japan. In Russia, they are found in Kamchatka and the Kuril Islands. Their populations have disappeared from large areas where they used to flourish,^[3] shrinking by as much as 40 percent.^[4]

Introductions

In 1967, the Michigan Department of Natural Resources planted chinook in Lake Michigan and Lake Huron to control the alewife, an invasive species of nuisance fish from the Atlantic Ocean. Alewives then constituted 90% of the biota in these lakes. Coho salmon had been planted the year before and the program was a success. Chinook and Coho salmon thrived on the alewives and spawned in the lakes' tributaries. After this success, chinook were planted in the other Great Lakes,^[5] where sport fishermen prize them for their aggressive behavior on the hook.

The species has also established itself in Patagonian waters in South America, where escaped hatchery fish have colonized rivers and established stable spawning runs.

It was introduced into New Zealand waters at the beginning of the twentieth century, where it flourishes. With the aid of hatchery stocking it has established spawning runs in Rangitata River, the Opihi River, the Ashburton River, the Rakaia River, the Waimakariri River, the Hurunui River, and the Waiau River.^[6] While other salmon were introduced into New Zealand, only chinook (or quinnat as it is known locally in NZ) has established sizeable pelagic runs.

The Yukon River has the longest freshwater migration route of any salmon, over 3,000 kilometers (1,864 mi) from its mouth in the Bering Sea to spawning grounds upstream of Whitehorse, Yukon. Since chinook rely on fat reserves for energy upon entering fresh water, commercial fish caught here are highly prized for their unusually high levels of heart-healthy omega-3 fatty acids. However, the high cost of harvest and transport from this exceptionally rural community limits its affordability.

• 

  Male ocean phase Chinook

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  Male freshwater phase Chinook

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  School of Chinook salmon

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  Sportfishing for Chinook salmon

First, salmon need to be able to have these kinds of foods: planktonic diatoms, copepods, kelps, seaweeds, jellyfish, and starfish. 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 until they are strong enough to journey out into the ocean and acquire more food. Chinook juveniles divide into two types: ocean type and stream type. Ocean type chinook migrate to saltwater in their first year. Stream type spend one full year in fresh water before migrating to the ocean. After a couple of years in the ocean, adult salmon, then large enough to escape most predators, return to their original streambeds to mate. Chinook salmon can have an extended lifespan, where some fish spend one to five years in the ocean reaching age eight. More northerly populations tend to have longer lives.

Second, salmon need adequate spawning habitat. Clean, cool, oxygenated sediment-free freshwater is essential for egg development. Chinook prefer larger sediment sizes for spawning than other pacific salmon. Riparian vegetation and woody debris help juvenile salmon by providing cover and maintaining low water temperatures.

Third, chinook need healthy ocean habitat. Juvenile salmon grow in clean, productive estuarine environments and gain the energy for migration. Later they change physiologically to live in saltwater. They rely on eelgrass and other seaweeds for camouflage (protection from predators), shelter, and foraging habitat as they make their way to the open ocean. Adult fish need a rich, open ocean habitat to acquire the strength that is needed to travel back upstream, escape predators, and reproduce before dying. 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 sustain 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 algae levels lead to higher levels of carbon dioxide in the water which transfers into living organisms, fostering underwater plants and small organisms, which salmon eat.^[7] Algae can filter 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 well-being of the food chain.

Finally, salmon need other salmon to survive so that they can reproduce and pass on their genes in the wild. With some populations endangered, precautions are necessary to prevent overfishing and habitat destruction, including appropriate management of hydroelectric and irrigation projects. If too few fish remain because of fishing and land management practices, salmon have more difficulty reproducing.

When one of these five factors is compromised, affected stock can decline. 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.^[4]

Management

Nine populations of chinook salmon are listed under the U.S. Endangered Species Act as either threatened or endangered.^[8] Fisheries in the U.S. and Canada are limited by impacts to weak and endangered salmon runs. The fall and late-fall runs in the Central Valley population in California is a U.S. National Marine Fisheries Service Species of Concern. Species of Concern are those species about which the U.S. Government’s National Oceanic and Atmospheric Administration, National Marine Fisheries Service, has some concerns regarding status and threats, but for which insufficient information is available to indicate a need to list the species under the U.S. Endangered Species Act.

In April 2008 commercial fisheries in both Oregon and California were closed due to the extremely low population of chinook salmon present. The low population is being blamed on the collapse the Sacramento River run, one of the biggest south of the Columbia.^[9] In April 2009 California again canceled the season.^[10] The Pacific Fishery Management Council’s goal for the Sacramento River run is an escapement total (fish that return to freshwater spawn areas and hatcheries) of 122,000–180,000 fish. The 2007 escapement was estimated at 88,000 and the 2008 estimate was 66,000 fish.^[11] Scientists from Universities and Federal, State, and Tribal Agencies concluded that the 2004 and 2005 broods were harmed by poor ocean conditions in 2005 and 2006, in addition to “a long-term, steady degradation of the freshwater and estuarine environment.” Such conditions included weak upwelling, warm sea surface temperatures, and low densities of food.^[11]

In Oregon, the 2010 Spring Chinook run is forecast to increase by up to 150% over 2009 populations, growing from 200,000 to over 500,000, making this the largest run in recorded history. Lower temperatures in 2008 North Pacific waters brought in fatter plankton which, along with greater outflows of Columbia River water, feeding the resurgent populations. The Oregon Department of Fish and Wildlife estimates that 80% of them are hatchery-born. Chinook runs in other habitats have not recovered proportionately.^[12]

Chinook in Culture and Commerce

Described and enthusiastically eaten by the Lewis and Clark Expedition, the chinook salmon is spiritually and culturally prized among certain Native American tribes. Many celebrate the first spring chinook caught each year with "First Salmon Ceremonies". While salmon fishing is still important economically for many tribal communities, the chinook harvest is typically the most valuable.

Known as the "king salmon" in Alaska for its large size and flavorful flesh, the chinook is the state fish.

See also

• Salmon in aquaculture

References

This article includes a list of references, but its sources remain unclear because it has insufficient inline citations. Please help to improve this article by introducing more precise citations where appropriate. (September 2010)

• "Oncorhynchus tshawytscha". Integrated Taxonomic Information System. http://www.itis.gov/servlet/SingleRpt/SingleRpt?search_topic=TSN&search_value=161980. Retrieved 30 January 2006. 
• Froese, Rainer, and Daniel Pauly, eds. (2005). "Oncorhynchus tshawytscha" in FishBase. 10 2005 version.
• 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.
• Montgomery, David. King of Fish: The Thousand-Year Run of Salmon. Boulder, CO: Westview Press, 2003.

External links

Wikimedia Commons has media related to: Oncorhynchus tschawytscha

• Fish Passage Center, monitoring salmon spawning and migration
• ESA Chinook Listings
• Potential causes of size trends in Yukon River chinook salmon populations / prepared by the United States and Canada Yukon River Joint Technical Committee, Salmon Size Subcommittee. Hosted by the Alaska State Publications Program.
• Spawning abundance of chinook salmon in the Chickamin River in 2004 / by Glenn M. Freeman, Scott A. McPherson, and Daniel J. Reed. Hosted by Alaska State Publications Program
• Season/Timing information for King Salmon in the Great Lakes region

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