| Chinook "king" salmon | |
|---|---|
| A male Chinook in its freshwater phase | |
| Scientific classification | |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Actinopterygii |
| Order: | Salmoniformes |
| Family: | Salmonidae |
| Genus: | Oncorhynchus |
| Species: | O. tshawytscha |
| Binomial name | |
| Oncorhynchus tshawytscha (Walbaum, 1792) |
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The Chinook salmon, Oncorhynchus tshawytscha, is the largest species in the pacific (Oncorhynchus) salmon family. Other commonly used names for the species include King salmon, Quinnat salmon, Spring salmon and Tyee salmon. Chinook are an anadromous fish native to the north Pacific Ocean and the river systems of western North America ranging from California to Alaska. They are also native to Asian rivers ranging from northern Japan to the the Palyavaam River in the Siberian far east, although only the Kamchatka Peninsula supports relatively persistent native populations. They have been introduced to other parts of the world, including New Zealand and the Great Lakes. A large Chinook is a prized and sought after catch for a sporting angler. The flesh of the salmon is also highly valued for its dietary nutritional content which includes high levels of important Omega-3 fatty acids.
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The Chinook is blue-green,red 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 92 pounds (42 kg) and was caught in 1928 in the Skeena River (Terrace, British Columbia). some were found dead at well over 100 lb. The commercial catch world record is 126 pounds (57 kg) caught near Rivers Inlet British Columbia in the late 1970s.[1] In the Pacific Northwest, the especially large summer runs of Chinook that were once common (before dams and overfishing lead to declines) were known as June Hogs.
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.[2]
Historically, the native distribution of Chinook salmon ranged from as far south as the Ventura River in California and north to Alaska, as far as Kotzebue Sound. In Asia and the western Pacific, they are consistently present only in Kamchatka. Elsewhere distribution is patchy, but occurs from northern Japan in the south and north into the Arctic Ocean as far as the East Siberian Sea and Palyavaam River.[3] Their populations have disappeared from large areas where they used to flourish,[4] shrinking by as much as 40 percent.[5] In North America their inland range has been cut off, mainly by dams and habitat alterations, from Southern California, some areas east of the Coast Ranges of California and Oregon, and large areas in the Snake River and upper Columbia River drainage basins.[3] Their distribution and presence in Russia is not fully known outside Kamchatka. They have a patchy presence in the Anadyr River basin and parts of the Chukchi Peninsula. In parts of northern Magadan Oblast near the Shelikhov Gulf and Penzhina Bay there might be persistent populations, but stocks there are poorly studied.[3]
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,[6] 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. Chinook salmon have been found spawning in headwater reaches of the Rio Santa Cruz, apparently having migrated over 1,000 kilometres (620 mi) from the ocean. The population is thought to be derived from a single stocking of juvenile chinooks in the lower river around 1930.[7]
Sporadic efforts to introduce the fish to New Zealand waters in the late 1800s were largely failures and lead to no evident establishments. Early ova were imported from the Baird hatchery of the McCloud River in California.[8] Further efforts in the early 1900s were more successful and subsequently lead to the establishment of spawning runs in the rivers of Cantebury and North Otago; Rangitata River, the Opihi River, the Ashburton River, the Rakaia River, the Waimakariri River, the Hurunui River, and the Waiau River.[9] The success of the latter introductions is thought to be partly attributable to the use of ova from Autumn run populations as opposed to ova from Spring run populations used in the first attempts.[8] Whilst other salmon have also been 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 kilometres (1,900 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.
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.[10] 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.[5]
Nine populations of chinook salmon are listed under the U.S. Endangered Species Act as either threatened or endangered.[11] 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.[12] In April 2009 California again canceled the season.[13] 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.[14] 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.[14]
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.[15]
Despite the use of hatcheries as enhancement tools for the wild stocks, there is currently no commercial aquaculture production of Chinook salmon in the United States.
The worlds' largest producer and market supplier of the Chinook salmon is in fact New Zealand. Marketed as King Salmon, in 2009, New Zealand exported 5,088 tonnes of salmon equating to a value of NZ$61 million in export earnings. For the year ended March 2011 this amount had increased to NZ$85 million.[16],[17] New Zealand accounts for approximately half of the global production of Chinook Salmon and approximately half of New Zealand's production is exported. Japan is New Zealand's largest export market with stock also being supplied to other countries of the Pacific rim including Australia.[18]
Farming of the species in New Zealand began in the 1970's where hatcheries were initially set up to enhance and support wild fish stocks with the first commercial operations initiating in 1976.[8] After some opposition against their establishment by societal groups including anglers, the first sea cage farm was established in 1983 at Big Glory Bay in Stewart Island by British Petroleum NZ Ltd. [8][18] Today the salmon are born in land based hatcheries (of which there are several) and transferred to sea cages or fresh water farms where they are grown out to harvestable size of 3 – 4kgs. The broodstock for the farms are usually selected from existing farm stock or sometimes sourced from wild populations. Eggs and milt are stripped manually from sexually mature salmon and incubated under conditions (of approximately 10 – 12˚C) replicating the streams and rivers where the salmon would spawn naturally. After hatching the baby salmon are typically grown to smolt stage (approximately 6 months of age) before they are transferred to the sea cages or ponds.[17] Most sea cage farming occurs in the Marlborough Sounds, Stewart Island and Akaroa Harbour, while fresh water operations in Canterbury, Otago and Tasman utilise ponds, raceways and hydro canals for grow out operations.[16] Low stocking densities, ranging between less than 1 kg/m3 up to around 25 kg/m3 (depending on the life stage of the salmon) and the absence of disease in the fish means that New Zealand farmers do not need to use antibiotics or vaccines to maintain the health of their salmon stocks. The salmon are fed food pellets of fish meal specially formulated for Chinook salmon (typical proportions of the feed are: 45% protein, 22% fat, 14% carbohydrate plus ash and water) and contain no steroids or other growth enhancers.[17][16]
Regulations and monitoring programmes ensure salmon are farmed in a sustainable manner. Planning and approval process for new salmon farms in New Zealand considers the farm’s potential environmental effects, its effects on fishing activities (if it is a marine farm), and any possible cultural and social effects. In the interest of fish welfare a number of New Zealand salmon farming operations anaesthetise salmon before slaughter using Aqui-S™. This is an organically based anaesthetic developed in New Zealand that is safe for use in food and which has been favourably reported on by the British Humane Slaughter Association. In recognition of the sustainable, environmentally conscious practices, the New Zealand salmon farming industry has been acknowledged as the world's greenest by the Global Aquaculture Performance Index.[19]
Globally, Chile is the only country other than New Zealand to produce any significant quantities of farmed Chinook salmon. New Zealand will likely remain the major producer of the species as other countries' (predominantly Norway, Canada and the United Kingdom) salmon productions are focused typically on other species such as Atlantic Salmon and Coho Salmon.
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.
Chinook salmon were described and enthusiastically eaten by the Lewis and Clark Expedition. Lewis wrote that, when fresh, they tasted better than any other fish he had ever eaten. They did not particularly like dried or "pounded" salmon.[20] Lewis and Clark knew about Pacific salmon but had never seen one. The Western world had known about Pacific salmon since the late 18th century. Maritime fur traders and explorers like George Vancouver frequently acquired salmon by trade with the indigenous people of the Northwest coast.[21] Lewis and Clark first encountered Chinook salmon as a gift from Chief Cameahwait, on August 13, 1805, near Lemhi Pass. Tasting it convinced Lewis that they had crossed the continental divide.[22]
Known as the "king salmon" in Alaska for its large size and flavorful flesh, the chinook is the state fish.
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