Chinook Salmon

Exemplar de salmó reial del Pacífic

Cries de salmó reial del Pacífic

Oncorhynchus tshawytscha, probablement mascle, en el moment de la reproducció en aigua dolça

Exemplar de salmó reial del Pacífic en fase de fresa

Mascle de salmó reial del Pacífic

Fase oceànica

Fase d'aigua dolça (vegeu les diferències en les mandíbules i el canvi de color)

El salmó reial o salmó reial del Pacífic^[1] (Oncorhynchus tshawytscha) és una espècie de peix de la família dels salmònids i de l'ordre dels salmoniformes.

Morfologia

• Els mascles poden assolir 150 cm de longitud total^[2] i 61,4 kg de pes.^[3]
• Nombre de vèrtebres: 67-75.^[4]

Depredadors

És depredat per la perca americana, Ptychocheilus oregonensis, el llobarro atlàntic ratllat, Sander vitreus, Megalocottus platycephalus, la truita de Clark, la truita arc de Sant Martí, Salvelinus malma malma, el salmó platejat, la foca comuna i el tauró dormilega del Pacífic.^[5]

Hàbitat

Viu a zones d'aigües dolces, salobres i marines temperades (72°N-27°N, 136°E-109°W) fins als 375 m de fondària.^[6][4]

Distribució geogràfica

Es troba des de Point Hope (Alaska)^[7][8] fins al riu Ventura (Califòrnia, Estats Units), tot i que, ocasionalment, ha estat vist fins a San Diego (Califòrnia). També és present a Honshu (el Japó),^[9] el mar del Japó, el mar de Bering,^[9][10] el mar d'Okhotsk^[11][12] i el riu Coppermine (l'Àrtic canadenc).^[4]

Longevitat

Pot arribar a viure 9 anys.^[13]

Referències

Bibliografia

Enllaços externs

• AQUATAB (anglès)

Losos čavyča (Oncorhynchus tshawytscha (Walbaum, 1792)), někdy také losos královský nebo losos stříbrný^[1], je ryba z čeledi lososovitých žijící v severní části Tichého oceánu a ve sladkých vodách jeho úmoří. Patří mezi potravu kosatky dravé.

Popis

Dorůstají velikosti až 1,47 m a váhy až 60 kg.^[2]

Rozmnožování

Táhnou v období od května do června. Někdy i více než 2000 km.^[2]

Rybolov

Kazdoročně je lososů čavyča vyloveno 20 tisíc tun. Většina produkce pochází z uměle chovaných populací v akvakulturních nádržích. Maso čavyči má růžovou až červenou barvu. Zpracovává se podobně jako losos obecný.^[3]

Nemoci

Druh je náchylný k nákaze virem způsobujícím infekční hematopoetickou nekrózu (IHN).^[4]

Odkazy

Reference

1. ↑ ^{a b} BioLib.cz – Oncorhynchus tshawytscha [online]. BioLib.cz. Dostupné online.
2. ↑ ^{a b} ryby - Tažní lososi Pacifiku a Severního led. oceánu (pdf)
3. ↑ BUCHTOVÁ, Hana: Hygiena a technologie produktů rybolovu, str.21, Brno 2012. (pdf)
4. ↑ Neexotické nákazy (pdf)

Externí odkazy

• Obrázky, zvuky či videa k tématu losos čavyča ve Wikimedia Commons
• Taxon Oncorhynchus tshawytscha ve Wikidruzích
• Onchorynchus tshawytscha : fisheries, aquaculture, gamefish [online]. Příprava vydání Rainer Froese, Daniel Pauly. FishBase, 2014. Dostupné online. (anglicky)

Der Königslachs oder Quinnat (Oncorhynchus tshawytscha) kommt vor allem in den Gewässern Russlands, Japans und Nordamerikas vor.

Aussehen

Vor der Laichwanderung ist der Rücken noch graugrün und der silberne Bauch ist mit schwarzen Flecken bedeckt. Während der Laichwanderung verändert er sein Aussehen. Der Rücken und die Seiten werden etwas bläulich und der Bauch bekommt rote Tupfen. Ältere männliche Fische können auch ganz rot werden. Männliche Königslachse können bis zu 150 cm lang und 36 kg schwer und Weibchen 120 cm lang und 20 kg schwer werden.

Verhalten

Die Geschlechtsreife tritt bei diesen Tieren normalerweise zwischen 4 und 6 Jahren ein. Bei Geschlechtsreife wandern die Königslachse von ihren Jagdgebieten vor der Meeresküste in ihre Heimatfließgewässer auf, wo sie schließlich laichen. Bei ihren Laichwanderungen können diese Fische über 40 km am Tag zurücklegen und 3,60 m hohe Wasserfälle überwinden. In den Flüssen legen sie Strecken bis zu 4000 km zu ihren Laichplätzen zurück. Die jungen Fische bleiben zwischen 1 und 3 Jahren im Süßwasser, bevor sie zu den Flussmündungen schwimmen.

Die weiten Wanderungen zwischen Geburtsgewässer und offenem Meer werden bei Königslachs, Rotlachs und Ketalachs auf deren Magnetsinn zurückgeführt.^[1]

Nahrung

Jungfische fressen erst Insektenlarven und Kleinkrebse, später auch kleine Fische wie Elritzen, Groppen und Schmerlen. Erwachsene Fische hingegen ernähren sich von Krebstieren und Fischen wie Sprotten, Makrelen und Heringen.

Königslachs und Mensch

Durch menschlichen Einfluss kommen Königslachse auch in Lebensräumen vor, die sich vom natürlichen Verbreitungsgebiet stark unterscheiden. So wurde diese Fischart seit 1967 im Bereich der Großen Seen und ihrer Zuflüsse – also in einer kompletten Süßwasser-Umgebung – angesiedelt, wo sich der Bestand seitdem gut etabliert und an die Gegebenheiten angepasst hat.^[2]

Bei den Eskimos hat der Königslachs eine besondere kulturelle und religiöse Bedeutung. Er ist Nahrungsmittel und Teil der jahreszeitlichen Rituale. Unter dem Einfluss der globalen Erwärmung nehmen die Bestände in Alaska seit etwa der Jahrtausendwende massiv ab. Im Delta des Yukon River wurde 2012 ein Fangverbot als Mittel des Artenschutzes verhängt. Einheimische Eskimos hielten sich aus kulturellen Gründen nicht daran und wurden im Sommer 2013 zu absichtlich sehr geringen Strafen verurteilt. Sie haben gegen das Urteil Berufung eingelegt und hoffen, dass das Alaska Supreme Court wie in mindestens einem früheren Fall die kulturelle Subsistenz-Jagd und -Fischerei als Religionsausübung nach dem 1. Zusatzartikel zur Verfassung der Vereinigten Staaten als geschützt ansieht.^[3]

Fußnoten

1. ↑ Kenneth J. Lohmann, Nathan F. Putman und Catherine M. F. Lohmann: Geomagnetic imprinting: A unifying hypothesis of long-distance natal homing in salmon and sea turtles. In: PNAS. Band 105, Nr. 49, 2008, S. 19096–19101, doi:10.1073/pnas.0801859105.
2. ↑ Kurt F. de Swaaf: Neue Stämme: Die Turbo-Evolution der Königslachse. In: Spiegel Online. 8. Januar 2012
3. ↑ The Atlantic: When Global Warming Kills Your God, 3. Juni 2014

Iqalugruaq

Iqalugruaq suli Qalugruaq (Oncorhynchus tshawytscha)

The Chinook salmon /ʃɪˈnʊk/ (Oncorhynchus tshawytscha) is the largest and most valuable species of Pacific salmon in North America, as well as the largest in the genus Oncorhynchus.^[2] Its common name is derived from the Chinookan peoples. Other vernacular names for the species include king salmon, Quinnat salmon, Tsumen, spring salmon, chrome hog, Blackmouth, and Tyee salmon. The scientific species name is based on the Russian common name chavycha (чавыча).

Chinook are anadromous fish native to the North Pacific Ocean and the river systems of western North America, ranging from California to Alaska, as well as Asian rivers ranging from northern Japan to the Palyavaam River in Arctic northeast Siberia. They have been introduced to other parts of the world, including New Zealand and Patagonia. Introduced Chinook salmon are thriving in Lake Michigan and Michigan's western rivers. 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. Some populations are endangered; however, many are healthy. The Chinook salmon has not been assessed for the IUCN Red List. According to NOAA, the Chinook salmon population along the California coast is declining from factors such as overfishing, loss of freshwater and estuarine habitat, hydropower development, poor ocean conditions, and hatchery practices.^[3]

Distribution

A male Chinook in his spawning phase

Natural range

Historically, the native distribution of Chinook salmon in North America ranged from the Ventura River in California in the south to Kotzebue Sound in Alaska in the north.^[4] Recent studies have shown that Chinook salmon are historically native to the Guadalupe River (California) watershed, the southernmost major metropolitan area hosting salmon runs in the United States.^[5] Populations have disappeared from large areas where they once flourished, however,^[6] or shrunk by as much as 40 percent.^[7] In some regions, their inland range has been cut off, mainly by dams and habitat alterations: in Southern California, in some areas east of the Coast Ranges of California and Oregon, and in large areas in the Snake River and upper Columbia River drainage basins.^[8] In certain areas such as California's Sacramento–San Joaquin River Delta, it was revealed that extremely low numbers of juvenile Chinook salmon (less than 1%) were surviving.^[9]

In the western Pacific, the distribution ranges from northern Japan (Hokkaido) in the south to the Arctic Ocean as far as the East Siberian Sea and Palyavaam River in the north.^[8] Nevertheless, they are consistently present and the distribution is well known only in Kamchatka. Elsewhere, information is scarce, but they have a patchy presence in the Anadyr River basin and parts of the Chukchi Peninsula. Also, in parts of the northern Magadan Oblast near the Shelikhov Gulf and Penzhina Bay, stocks might persist but remain poorly studied.^[8]

Introduced populations

In 1967, the Michigan Department of Natural Resources introduced Chinook into Lake Michigan and Lake Huron to control the alewife, an invasive species of nuisance fish from the Atlantic Ocean.^[10] In the 1960s, alewives constituted 90% of the biota in these lakes. Coho salmon had been introduced the year before, and the program was successful. Chinook and Coho salmon thrived on the alewives and spawned in the lakes' tributaries. After this success, Chinook were introduced into the other Great Lakes,^[11] where sport fishermen prize them for their aggressive behaviour on the hook.

The species has also established itself in Patagonian waters in South America, where both introduced and escaped hatchery fish have colonized rivers and established stable spawning runs.^[12] Chinook salmon have been found spawning in headwater reaches of the Rio Santa Cruz, apparently having migrated over 1,000 km (620 mi) from the ocean. The population is thought to be derived from a single stocking of juveniles in the lower river around 1930.^[13]

Sporadic efforts to introduce the fish to New Zealand waters in the late 19th century were largely failures and led to no evident establishments. Initially ova were imported from the Baird hatchery of the McCloud River in California.^[14] Further efforts in the early 20th century were more successful and subsequently led to the establishment of spawning runs in the rivers of Canterbury and North Otago: Rangitata River, the Opihi River, the Ashburton River, the Rakaia River, the Waimakariri River, the Hurunui River, and the Waiau Uwha River.^[15] 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.^[14] Whilst other salmon have also been introduced into New Zealand, only Chinook salmon (or king salmon as it is known locally in New Zealand) have established sizeable pelagic runs.

Description

A pair of chinook caught in the ocean

Chinook salmon tail, showing distinctive combination of black spots and silver

The Chinook is blue-green, red, or purple on the back and on the 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. Although spots are seen on the tail in pink salmon and silver on the tail in coho and chum salmon, Chinook are unique among the Pacific salmon in combining black spots and silver on the tail. Another distinctive feature is a black gum line that is present in both salt and fresh water.^[16] Adult fish typically range in size from 24 to 36 in (61 to 91 cm), but may be up to 58 in (150 cm) in length; they average 10 to 50 lb (4.5 to 22.7 kg), but may reach 130 lb (59 kg). The meat can be either pink or white, depending on what the salmon have been feeding on.

Chinook salmon are the largest of the Pacific salmon. In the Kenai River of Alaska, mature Chinook averaged 16.8 kg (37 lb).^[17] The current sport-caught world record, 97.25 lb (44.11 kg), was caught on May 17, 1985, in the Kenai River. The commercial catch world record is 126 lb (57 kg) caught near Rivers Inlet, British Columbia, in the late 1970s.^[18]

Life cycle

Fertilized Chinook eggs

Chinook, like many other species of salmon, are considered euryhaline, and thus live in both saltwater and freshwater environments throughout their life. Once hatching, salmon spend one to eight years in the ocean (averaging from three to four years)^[19] before returning to their home rivers to spawn. The salmon undergo radical morphological changes as they prepare for the spawning event ahead. Salmon lose the silvery blue they had as ocean fish, and their color darkens, sometimes with a radical change in hue. Salmon are sexually dimorphic, and the male salmon develop canine-like teeth, and their jaws develop a pronounced curve or hook called a "kype."^[20] Studies have shown that larger and more dominant male salmon have a reproductive advantage as female Chinook are often more aggressive toward smaller males.^[21]

Chinook spawn in larger and deeper waters than other salmon species and can be found on the spawning redds (nests) from September to December. The female salmon may lay her eggs in four to five nesting pockets within a redd. After laying eggs, females guard the redd from four to 25 days before dying, while males seek additional mates. Chinook eggs hatch 90 to 150 days after deposition, depending upon water temperature. Egg deposits are timed to ensure the young salmon fry emerge during an appropriate season for survival and growth. Fry and parr (young fish) usually stay in fresh water for 12 to 18 months before traveling downstream to estuaries, where they remain as smolts for several months. Some Chinook return to fresh water one or two years earlier than their counterparts and are referred to as "jack" salmon. "Jack" salmon are typically less than 24 inches (61 cm) long but are sexually mature.

Chinook salmon (male)

Ocean-phase

Spawning phase, showing more curved jaws and change in colour

The Yukon River has the longest freshwater migration route of any salmon, over 3,000 km (1,900 mi) from its mouth in the Bering Sea to spawning grounds upstream of Whitehorse, Yukon.^[22] Since Chinook rely on fat reserves for energy upon re-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 costs of harvest and transport from this rural area limits its affordability. The highest elevation Chinook spawn is in the Middle Fork and Upper Salmon River in Idaho. These fish travel over 7,000 feet (2,100 m) in elevation, and over 900 miles (1,400 km), in their migration through eight dams and reservoirs on the Columbia and Lower Snake Rivers.

Chinook eat amphipods and other crustaceans and insects while young, and primarily other fish when older. Young salmon feed in streambeds for a short period until they are strong enough to journey out to the ocean and acquire more food. Chinook juveniles divide into two types: ocean-type and stream-type. Ocean-type Chinook migrate to salt water in their first year. Stream-type salmon spend one full year in fresh water before migrating to the ocean. After a few years in the ocean, adult salmon, then large enough to escape most predators, return to their natal streambeds to mate. Chinook can have extended lifespans, in which some fish spend one to five years in the ocean, reaching age eight. More northerly populations tend to have longer lives.

School of Chinook

Salmon need suitable spawning habitat. Clean, cool, oxygenated, sediment-free fresh water is essential for egg development. Chinook use larger sediment (gravel) sizes for spawning than other Pacific salmon. Riparian vegetation and woody debris help juvenile salmon by providing cover and maintaining low water temperatures.

Chinook also need healthy ocean habitats. Juvenile salmon grow in clean, productive estuarine environments and gain the energy for migration. Later, they change physiologically to live in salt water. They rely on eelgrass and 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 needed to travel back upstream, escape predators, and reproduce before dying. In his book King of Fish, David Montgomery writes, "The reserves of fish at sea are important to restocking rivers disturbed by natural catastrophes." Thus, it is vitally important for the fish to reach the oceans to grow into healthy adult fish to sustain the species without being impeded by man-made structures such as dams.

The bodies of water for salmon habitat must be clean and oxygenated. One sign of high productivity and growth rate in the oceans is the level of algae. Increased algal 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.^[23] Algae can filter high levels of toxins and pollutants. Thus, it is essential for algae and other water-filtering agents not to be destroyed in the oceans because they contribute to the well-being of the food chain.

Chinook salmon moving upstream

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 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 it is imperative for people to realize the needs of salmon and try not to contribute to destructive practices that harm salmon runs.^[7]

In the Pacific Northwest, the summer runs of especially large Chinook once common (before dams and overfishing led to declines) were known as June hogs.

A Chinook's birthplace and later evolution can be tracked by looking at its otolith (ear) bone. The bone can record the chemical composition of the water the fish had lived in, just as a tree's growth rings provide hints about dry and wet years. The bone is built with the chemical signature of the environment that hosted the fish. Researchers were able to tell where different individuals of Chinook were born and lived in the first year of their lives. Testing was done by measuring the strontium in the bones. Strontium can accurately show researchers the exact location and time of a fish swimming in a river.^[24]

Fishing industry

Global harvest in thousand tonnes as reported by the FAO, 1950–2010^[25]

Wild capture

Wild capture in thousand tonnes as reported by the FAO, 1950–2010^[25]

Wild capture as reported by the FAO for 2010^[25]

The total North Pacific fisheries harvest of the Chinook salmon in 2010 was some 1.4 million fish, corresponding to 7,000 tonnes; 1.1 million of the fish were captured in the United States, and others were divided by Canada and Russia. The share of Chinook salmon from the total commercial Pacific salmon harvest was less than 1% by weight and only about 0.3% of the number of fish.^[26] The trend has been down in the captures compared to the period before 1990, when the total harvest had been around 25,000 tonnes. Global production has, however, remained at a stable level because of increased aquaculture.^[25]

Aquaculture

Aquaculture production as reported by the FAO for 2010^[25]

The world's largest producer and market supplier of Chinook salmon is New Zealand. In 2009, New Zealand exported 5,088 tonnes (5,088 t) of Chinook salmon, marketed as king 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.^[27][28] New Zealand accounts for about half of the global production of Chinook salmon, and about 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.^[29]

Farming of the species in New Zealand began in the 1970s when hatcheries were initially set up to enhance and support wild fish stocks, with the first commercial operations starting in 1976.^[14] 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.^[14][29] Today, the salmon are hatched in land-based hatcheries (several of which exist) and transferred to sea cages or freshwater farms, where they are grown out to the harvestable size of 3–4 kilograms (6.6–8.8 lb). The broodstock for the farms is 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 replicating the streams and rivers where the salmon would spawn naturally (at around 10–12 °C or 50–54 °F). After hatching, the baby salmon are typically grown to the smolt stage (around six months of age) before they are transferred to the sea cages or ponds.^[28] Most sea cage farming occurs in the Marlborough Sounds, Stewart Island, and Akaroa Harbour, while freshwater operations in Canterbury, Otago, and Tasman use ponds, raceways, and hydro canals for grow-out operations.^[27] Low stocking densities, ranging between less than 1 kg/m³ and around 25 kg/m³ (depending on the life stage of the salmon), and the absence of disease in the fish mean 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, and 14% carbohydrate plus ash and water) that contain no steroids or other growth enhancers.^[27][28]

Aquaculture production in thousand tonnes as reported by the FAO, 1980–2010 ^[25]

Regulations and monitoring programmes ensure salmon are farmed in a sustainable manner. The 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™, an organically based anaesthetic developed in New Zealand that is safe for use in food and that 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.^[30]

Chile is the only country other than New Zealand currently producing significant quantities of farmed Chinook salmon.^[25] The United States has not produced farmed Chinook in commercial quantities since 1994.^[25] In Canada, most commercial Chinook salmon farming ceased by 2009.^[31]

Management

Pacific coast

Fisheries in the U.S. and Canada are limited by impacts to weak and endangered salmon runs. Nine populations of Chinook salmon are listed under the U.S. Endangered Species Act (ESA) as either threatened or endangered.^[32] In the Snake River, Spring/Summer Chinook and Fall Chinook are ESA listed as Threatened.^[33] The fall and late-fall runs in the Central Valley population in California is a U.S. National Marine Fisheries Service (NMFS) species of concern.

In April 2008, commercial fisheries in both Oregon and California were closed in response to the low count of Chinook salmon present because of the collapse of the Sacramento River run, one of the biggest south of the Columbia.^[34] In April 2009, California again canceled the season.^[35] 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.^[36] Scientists from universities and federal, state, and tribal agencies concluded 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.^[36]

In Oregon, the 2010 spring Chinook run was 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, fed the resurgent populations. The Oregon Department of Fish and Wildlife estimated 80% were hatchery-born. Chinook runs in other habitats have not recovered proportionately.^[37]

In April 2016, Coleman National Fish Hatchery outside of Red Bluff, California, released 12 million juvenile Chinook salmon, with many salmon being tagged for monitoring. The release was done in hopes of helping restore the salmon population of Battle Creek.^[38][39]

In June 2021, the California State Water Resources Control Board approved a plan by the United States Bureau of Reclamation to release water from Lake Shasta for irrigation use, which "significantly" increased the risk of extinction of winter-run Chinook in the Sacramento River.^[40]

Lake Michigan

Introduced Chinook salmon in Lake Michigan are sought after by tourists enjoying chartered fishing trips.^[41] A 2016 survey of Wisconsin anglers found they would, on average, pay $140 for a trip to catch Chinook salmon, $90 for lake trout, and $180 for walleye.^[42] Should the Chinook salmon fishery collapse and be replaced with a native lake trout fishery, the economic value would decrease by 80%.^[43]

Recent data

Since the later 1970s, the size and age range of Chinook salmon have been declining^[44] according to studies along the northwest Pacific coast from Alaska to California for the years of 1977 to 2015 which examined about 1.5 million Chinook salmon.^[44] Ocean-5 Chinook (which means the fish has spent five years in the ocean) have declined from being up to 3–5% of the population to being almost none.^[44] Ocean-4 chinook are also seeing a rapid decline in their population.^[44] This means that Chinook are not living as long as they used to. This trend has mostly been seen in Alaska, but also Oregon and Washington.^[44]

New trends have also been seen regarding the size of Ocean-1, 2, 3, 4, and 5 from 1975 to 2015. The size of Chinook who have spent one and two years in the ocean has been rising, while the size of Chinook of three to five years has been declining.^[44] The size increase was seen mainly in hatchery fish, not wild, and hatchery fish were often larger than wild, but the decrease was seen in both types of populations.^[44] Factors have been discovered that have influenced the size of the Chinook. They include, but are not limited to, the years they spent in fresh water before migrating to the ocean, the time of year they were caught, which season run they participated in, and where they were caught.^[44] However, what is causing these negative trends is still not fully known or researched. Some possibilities can be climate change, pollution, and fishing practices.^[44]

Juvenile Chinook salmon being measured for research

In California specifically, Chinook populations in the rivers have been declining.^[45] Chinook that are migratory are already more vulnerable, and the California drought made them even more vulnerable. A study was done specifically on the California Delta over three years, and it was discovered that the Chinook salmon had a low survival rate for different reasons, and as a result, the Chinook salmon population here has been on a decline.^[45] Some of the factors affecting the populations include the route used during migration, drought conditions, the amount of snowmelt, and infrastructure that affects the flow of water (such as dams and levees).^[45] Each of these factors has significantly impacted Chinook survival rates, as most have made it more challenging for Chinook to travel from their spawning grounds to the ocean and back. The fluctuation of water depth as well as temperature have made this more challenging, and as a result, Chinook populations are declining. Which rivers or streams the Chinook are in highly impacts their survival rates, as some, like the Chinook in the Fraser River, only have a 30% survival rate.^[45] More studies and actions are needed for there to be an impact on the survival rates of the Chinook. Due to many of these reasons, the National Wildlife Federation has listed Chinook populations as endangered or threatened.^[46]

Cultural aspects

Native American men with large salmon

The Chinook salmon is spiritually and culturally prized among certain First Nations peoples. For tribes on the Northwest coast, salmon were an important part of their culture for spiritual reasons and food.^[47] Many celebrate the first spring Chinook caught each year with "first-salmon ceremonies." While salmon fishing in general remains important economically for many tribal communities, it is especially the Chinook harvest that is typically the most valuable. The relation to salmon for the tribes in this area is similar to how other tribes relied more on buffalo for food, and have many legends and spiritual ties to them.^[47]

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.^[48] 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, such as George Vancouver, frequently acquired salmon by trade with the indigenous people of the Northwest coast.^[49] Lewis and Clark first encountered Chinook salmon as a gift from Chief Cameahwait, on August 13, 1805, near Lemhi Pass. Tasting it convinced Lewis they had crossed the continental divide.^[50]

In Oregon, the Klamath tribes have lived along the Klamath river, and the Chinook salmon have been a large part of their lives.^[51] An Indian legend of a tribe on the Klamath river describes how the construction of the dam has hurt the fish population and that the impact on them has gone unnoticed, and the destruction of the dam is what has brought back their food supply and made them happy again.^[51] The Klamath tribe had a similar legend that has illustrated the importance of not messing up the Chinook salmon migration.^[51] The legend described three Skookums which can be related to the three dams on the Klamath river in California.^[51] It has been known that the creation of dams has negatively impacted the lives of many Native American Indians by disrupting their food supply and the flow of water. The impact on the salmon migration has been seen by not only tribal members but others as well, and as a result, progress is slowly being made to help restore the salmon habitats along the river.^[51] It has been known that for many tribes Chinook salmon have played an important role, spiritually and physically.

Other tribes, including the Nuxalk, Kwakiutl, and Kyuquot, relied primarily on Chinook to eat.^[52] Known as the "king salmon" in Alaska for its large size and flavorful flesh, the Chinook is the state fish of this state,^[53] and of Oregon.^[54]

References

El salmón real (Oncorhynchus tshawytscha), chinuc o chinook (por su nombre en inglés), es un pez de la familia de los Salmonidae que se encuentra en las áreas costeras del océano Pacífico, entre California y Japón. Animal eurihalino, vive en el mar pero migra remontando los ríos para reproducirse (anádromo). Es muy valorado por su relativa escasez.

Descripción

Cardumen de salmón real.

Adulto mide entre 84 y 147 cm de longitud y pesa entre 25 y 60 kg. Es azul verdoso sobre el lomo y la cabeza, plateado en los flancos y blanco en el vientre. Presenta puntos negros en la cola y en la parte superior sel cuerpo; su boca es gris obscura.

El récord de captura en pesca deportiva es de 44,1 kg) registrado por el pescador Les Anderson en el río Kenai, Alaska, en 1985. En la pesca comercial el récord es de 57 kg registrado cerca de Petersburg, Alaska en una captura en 1949.^[1]​

Reproducción

Puede pasar entre tres y cinco años en el océano antes de retornar por los ríos para procrear y desovar en las aguas dulces donde nacieron. Prefiere corrientes más grandes y profundas que otras especies de salmón, y su desove ocurre entre septiembre y diciembre. (Hasta marzo en Chile).

Una vez en las partes altas de la corriente de agua dulce, la hembra elige al macho con el cual se reproducirá. Su selección se basa en las dimensiones físicas del varón. La hembra elige una zona de la cama del río en el cual haya grava en abundancia y allí cava un hueco poco profundo con la cola, mientras que el macho danza frente ella y hace vibrar su cuerpo. El número de huevos oscilan entre los 3 mil y 14 mil según el tamaño de la hembra y el macho los fertiliza súbitamente cuando ella los deposita.

La hembra protege los huevos entre 4 y 25 días mientras que el macho busca otras hembras. Ambos padres mueren tras reproducirse. De acuerdo con la temperatura del agua, los huevos se incuban entre 90 y 150 días antes de nacer los alevines. Después de 12 a 18 meses los ejemplares juveniles comienzan su migración hacia el mar.

Cambios en el cuerpo

Durante el período de la reproducción sufre algunas transformaciones morfológicas. Ambos sexos adquieren durante este tiempo una tonalidad rojiza brillante sobre los flancos, más intensa en los machos, que sufren incluso la modificación de la espalda, que se eleva y de la mandíbula inferior que curva hacia arriba e impide que la boca se cierre. Este crecimiento de la mandíbula vuelve prácticamente imposible que los adultos puedan alimentarse durante la fase de la reproducción, de manera que desde que empiezan su migración estacional hacia las fuentes de los ríos para reproducirse mantienen un ayuno absoluto.

Distribución

Pesca deportiva de salmón.

Se encuentra desde la bahía de San Francisco en California hacia el norte siguiendo la costa pacífica de Estados Unidos, Canadá y Alaska, el estrecho de Bering y el mar de Chukchi, el nororiente de Siberia, Rusia, la península de Kamchatka, las Islas Kuriles y las islas del Japón.

En 1967, el Departamento de Recursos Naturales de Míchigan soltó salmones reales en el lago Míchigan y en el lago Hurón para controlar la pinchagua o «tabernera» una especie invasiva procedente del océano Atlántico. Después de culminar con éxito esta implantación los salmones reales fueron llevados a otros de los Grandes Lagos,^[2]​ donde son apreciados para la pesca deportiva.

La especie se ha introducido en las costas de la Patagonia de Chile y Argentina donde ha colonizado ríos y establecido lugares estables de desove. También fue llevada con éxito a Nueva Zelanda.^[3]​

El río Yukón registra la más larga ruta de migración del salmón, más de 3 000 km desde el mar de Bering hasta las fuentes cerca de Whitehorse. Se construyó un canal en la represa hidroeléctrica del lago Schwatka para garantizar el paso y la reproducción del salmón real en Whitehorse.

Río Palena

Río Palena

Ecología

El salmón real necesita para sobrevivir:

1. alimento,
2. hábitat de desove,
3. hábitat oceánico,
4. aguas frías, limpias y con oxígeno suficiente, y
5. otros salmones

Toma del plancton para su alimentación diatomeas, copépodos, laminariales y macroalgas; además consume medusas, estrellas de mar, insectos, amfipódos, y otros crustáceos; y cuando está adulto se alimenta también de otros peces.

Las aguas limpias son esenciales para el desove. La vegetación ribereña ayuda a mantener las condiciones de las aguas para la reproducción y la vida juvenil del salmón real.

Algunas poblaciones de salmón de Estados Unidos están en la lista de especies amenazadas, por ejemplo la del Valle Central de California. En abril de 2008 tanto en Oregón como en California debió cancelarse la temporada de pesca debido a la baja población registrada. En el río Sacramento la población de la especie está al borde del colapso.^[4]​

En la cultura

El salmón real es espiritual y culturalmente muy preciado por los pueblos indígenas de las regiones donde habita originalmente, que celebren «ceremonias del salmón» en la primavera. Fue descrito y además consumido con entusiasmo por la expedición de Lewis y Clark (1804-06). La importancia económica para las comunidades indígenas y para otras poblaciones es muy grande. Es apreciado por su color, sabor, textura y alto contenido de aceite Omega-3.^[5]​

Notas

Referencias

• Sistema Integrado de Información Taxonómica. «Oncorhynchus tshawytscha (TSN 161980)» (en inglés).
• "Oncorhynchus tshawytscha". En FishBase (Rainer Froese y Daniel Pauly, eds.). Consultada en 10 de 2005. N.p.: FishBase, 2005.
• 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.

Oncorhynchus tshawytscha Oncorhynchus generoko animalia da. Arrainen barruko Salmonidae familian sailkatzen da.

Banaketa

Erreferentziak

• FishBase.org

Ikus, gainera

• Oncorhynchus
• Salmonidae

Kuningaslohi (Oncorhynchus tshawytscha) on tyynenmerenlohten sukuun kuuluva suuri kala. Se voi kasvaa puolitoistametriseksi ja 45–50-kiloiseksi. Kuningaslohen alkuperäistä asuinaluetta on pohjoinen Tyynimeri Japanista ja Koreasta aina Kaliforniaan asti. Nykyään kuningaslohta elää istutettuna eri puolilla maailmaa mm. Uudessa-Seelannissa.

Kuningaslohta on yritetty kotiuttaa myös Eurooppaan, aina tuloksetta. Suomessa istutuksia tehtiin vuosina 1935–1937 Kokemäenjokeen, Oulujokeen, Höytiäiseen ja eräisiin Pohjanmaan pienempiin jokiin. Luonnollinen lisääntyminen ei koskaan käynnistynyt.

Lähteet

• Hannu Lehtonen: Iso kalakirja – Ahvenesta vimpaan. WSOY, 2003. ISBN 951-0-28134-4.

Aiheesta muualla

• Oncorhynchus tshawytscha Luonnontieteellinen keskusmuseo.
• Oncorhynchus tshawytscha (peilipalvelin) FishBase. Froese, R. & Pauly, D. (toim.). (englanniksi)
• ITIS: Oncorhynchus tshawytscha (englanniksi)
• Oncorhynchus tshawytscha FAO Fisheries and Aquaculture Department. (englanniksi)

Saumon royal

Le saumon royal, saumon chinook, ou saumon quinnat (Oncorhynchus tshawytscha) est une espèce de poissons anadromes présents dans les eaux du nord de l'océan Pacifique. Il était autrefois présent dans les fleuves de la façade pacifique de l'Alaska à la Californie. Il en existe aussi des populations au Japon et dans les South Island de Nouvelle-Zélande.

C'est le plus grand des saumons américains. Il est aussi apprécié pour sa richesse en omega 3. C'est l'une des espèces de saumons nord-américaines les plus appréciées des pêcheurs sportifs.

Description

Saumons royaux pêchés vers 1910 (Astoria, Oregon)

Les chinooks doivent aussi affronter les pêcheurs "sportifs", ici les attendant en aval d'un seuil où les poissons doivent prendre leur élan pour sauter.

Saumon royal mâle sexuellement mature.

Livrée du mâle, et déformation de la mâchoire en eau douce.

Banc de saumons Chinook.

Saumon royal nageant dans une faible épaisseur d'eau pour rejoindre leurs frayères.

Ce saumon peut atteindre 1,5 m pour plus de 60 kg et une longévité de 9 ans.

Le Chinook est bleu-vert, violet sur le dos et le dessus de la tête avec les flancs argentés et le ventre blanc. Il porte des taches noires sur la queue et la moitié supérieure de son corps. Sa bouche est souvent de couleur violet foncé.

Le record actuel homologué en pêche sportive est de 45 kg pour un saumon capturé en 2002 dans le fleuve Skeena (Skeena river, Terrace, Colombie-Britannique). Pour les années récentes, le record mondial de capture commerciale homologué serait de 54 kg, pêché près du Fjord Rivers Inlet au nord-est du Canada en Colombie-Britannique dans les années 1970^[1].

Dans le patois de la région Pacifique du Nord-Ouest des États-Unis, les « Hogs » sont les saumons capturés lors de leur remontée migratoire. Dans cette région, l'été surtout, on pêchait de très grands saumons dits « June Hogs ». C'était l'une des principales ressources en poisson des peuples des Premières nations nord-amérindiennes. Ces saumons furent rapidement très appréciés des pêcheurs sportifs canadiens et américains, ainsi que des conserveries de saumon installées sur le fleuve Columbia et ses affluents. Ils ont disparu avec la surpêche et la construction des grands barrages. Aujourd'hui le plus grand Chinook pris dans les mêmes conditions sont deux fois plus petits que les « June hogs » capturés moins d'un siècle plus tôt.

Cycle de vie

Ce saumon peut passer de 1 à 8 ans dans l'océan (3 à 4 ans en moyenne^[2]) avant de remonter vers les sources de sa rivière natale pour frayer. Les Chinook se reproduisent dans les eaux nettement plus profondes que d'autres espèces de saumons. Le frai est déposé dans un nid sur le fond, de septembre à décembre. Après la ponte, les femelles gardent leur ponte 4 à 25 jours avant de mourir, tandis que les mâles cherchent à continuer à se reproduire. L'éclosion a lieu - selon la température de l'eau - 90 à 150 jours après la ponte. Les larves émergent au printemps, saison appropriée pour leur survie et croissance. Les larves et tacons (jeunes poissons) passent 12 à 18 mois en eau douce avant d'entamer leur dévalaison vers les estuaires, où ils grossissent (comme saumoneaux) durant plusieurs mois. Certains Chinook retournent vivre un ou deux ans après en eau douce, plus tôt que leurs homologues, et sont dits "Jack" (ils font la moitié de la taille d'un saumon adulte de la même espèce). Les pêcheurs sportifs les relâchent généralement, alors que les pêcheurs commerciaux les conservent^[2].

Habitat

Cette espèce vit de la baie de Monterey (Californie du nord) au détroit de Béring (Alaska) et jusque dans les eaux arctiques du Canada et de la Russie (Mer de Tchoukotka). Des populations se produisent en Asie jusqu'au sud des îles du Japon. Il y en a au Québec dans des lacs, des rivières et dans le fleuve St-Laurent. En Russie, on les trouve dans le Kamtchatka et les îles Kouriles, mais ils ont disparu d'une grande partie de leur aire de répartition^[3]. Au moins 40 % des populations ont disparu^[4].

Réintroductions et introductions

L'espèce a été réintroduite dans le lac Michigan et le lac Huron en 1967 par le Michigan Department of Natural Resources pour y contrôler le gaspareau, espèce atlantique devenue invasive après avoir été introduite dans les lacs où à cette époque il constituait environ 90 % du biote. Les saumons argentés (ou saumons coho), avaient été implantés avec succès l'année précédente et le chinook s'y est également réinstallé, jusque dans les affluents des lacs. Après ce succès, le saumon chinook a été implanté ou réimplanté dans les autres Grands Lacs^[5] où les pêcheurs sportifs l'ont apprécié pour sa résistance.

L'espèce est aussi apparue dans les eaux de Patagonie (Amérique du Sud, à partir d'individus relâchés ou échappés d'élevages. Ils y ont colonisé plusieurs fleuves où l'on observe maintenant des montaisons stables.

Des efforts sporadiques ont été faits dès la fin des années 1800 pour l'introduire en Nouvelle-Zélande avec plusieurs échecs successifs. Des tentatives ou réussites (à partir d'œufs ou alevins implantés dans les cours d'eau) ont eu lieu en Californie^[6] dès les années 1900, plus efficacement par la suite dans les rivières de Cantebury et North Otago ; Rangitata, la rivière Opihi, la rivière Ashburton, la rivière Rakaia, la rivière Waimakariri, le fleuve Hurunui et la rivière Waiau^[7]. On a attribué un taux de succès plus élevé pour les introductions récentes au fait qu'on a utilisé des ovules prélevés en automne plutôt qu'au printemps comme au lors des premières tentatives^[6]. Le Chinook et d'autres saumons ont aussi été introduits en Nouvelle-Zélande.

C'est dans le fleuve Yukon qu'est effectuée la plus longue route migratoire pour cette espèce (plus de 3 000 kilomètres, soit 1 900 milles de son embouchure dans la mer de Béring aux frayères située en amont de Whitehorse, dans le Yukon. Ces chinooks doivent compter sur d'importantes réserves de graisse pour avoir assez d'énergie pour franchir les nombreux obstacles qui les séparent de leurs frayères, et sont réputés être plus riches qu'ailleurs en acides gras oméga-3.

Études de cette espèce

Études des migrations

Dans le cadre d'un projet d'environ 600 millions de US dollars, sur le fleuve Columbia des puces RFID sont utilisées depuis 1986 pour étudier les corridors écologiques de migration et les dates et vitesse de migration des saumons chinook dans un réseau hydrogrphique qui compte divers obstacles naturels et environ 400 retenues d'eau plus ou moins artificielles sur son parcours (fleuve et affluents)^[8]. Une boucle du fleuve entoure le plus vaste complexe nucléaire américain (initialement construit pour produire le plutonium des bombes atomiques) et devenu le plus grand site de dépôt de déchets nucléaires, le site ayant libéré quand il était en activité une importante pollution radioactive dans ce fleuve, qui a notamment touché les saumons. Les 14 sous-espèces de chinook sont en disparition ou fort déclin, mais pas uniquement dans ce fleuve. Elles se sont dans tous les cours d'eau du Nord-Ouest du Pacifique où elles étaient encore abondantes il y a 2 ou 3 siècles, de même que la plupart des saumons dans le monde). Dans le fleuve Columbia près de deux millions de saumons ont ainsi été piégés et « taggés » puis relâchés chaque année depuis 1986^[8] ce qui a permis de repérer les zones dangereuses pour les poissons et d'y réduire les taux de mortalité de 15 à 20 %^[8].

Génomique, génie génétique

Cette espèce dont on trouvait autrefois de très gros individus intéressent l'industrie du génie génétique qui espèrent y trouver des gènes permettant de faire grossir d'autres poissons (comme le « saumon AquAdvantage » qui fait depuis plusieurs années l'objet d'une demande de mise sur le marché aux États-Unis)

• Par exemple, le promoteur du gène de la PRL (prolactine) isolé chez le saumon chinook (sPRL) a été transféré chez des lignées transgéniques de truites (truite arc-en-ciel transgénique ; Oncorhynchus mykiss) créées par microinjection de deux constructions génétiques issues du Chinook dans des œufs de truites^[9]. Ces deux construction contenaient le promoteur sPRL fusionné au gène rapporteur bactérien LacZ ou CAT. À l'Université de Rennes 1, un travail de thèse^[9] a en 1999 porté sur l'étude in vivo de l'activité CAT a montré qu'il n'était exprimé que par l'hypophyse, mais fortement. Alors que le gène LacZ s'est exprimé, via l'activité β-galactosidase dans la pars rostral de l'adénohypophyse, à l'intérieur de cellules spécialisées (« cellules à prolactine ») groupées en follicules, là où s'est également exprimée l'activité enzymatique^[9]. Cependant, toutes les cellules à prolactine n'expriment pas systématiquement le transgène^[9]. Lors de cette expérience, l'expression du gène LacZ (sous contrôle du promoteur sPRL) a été étudiée chez 13 familles ayant 9 profils électrophorétiques distincts de migration de l'ADN (familles de générations différentes) ; ce transgène ne s'est exprimé que chez 2/3 des familles et « quels que soient l'individu et la famille étudiés, toutes les cellules à prolactine n'expriment pas le transgène (variégation) et l'expression du transgène est variable entre 2 cellules d'un même individu et 2 individus d'une même famille^[9]. Cette variabilité d'expression pourrait résulter de la combinaison de différents facteurs comme la taille du promoteur, la forte quantité de copies de transgène intégré, la présence de séquences procaryotes, les effets inhibiteurs du gène rapporteur LacZ, ou encore l'utilisation de lignées non pures »^[9]. Il peut donc y avoir une variabilité d'expression du transgène dans des lignées stables de poissons transgéniques^[9].

Annexes

Références taxonomiques

• (en) Référence Animal Diversity Web : Oncorhynchus tshawytscha (consulté le 29 septembre 2014)
• (en) Référence Catalogue of Life : Oncorhynchus tshawytscha (Walbaum, 1792) (consulté le 16 décembre 2020)
• (fr+en) Référence FishBase : (consulté le 29 septembre 2014)
• (fr+en) Référence ITIS : Oncorhynchus tshawytscha (Walbaum in Artedi, 1792) (consulté le 29 septembre 2014)
• (en) Référence NCBI : Oncorhynchus tshawytscha (taxons inclus) (consulté le 29 septembre 2014)
• (en) Référence uBio : Oncorhynchus tshawytscha (Walbaum, 1792) (consulté le 29 septembre 2014)
• (en) Référence World Register of Marine Species : espèce Oncorhynchus tshawytscha (Walbaum, 1792) (consulté le 29 septembre 2014)

Notes et références

O salmón real,^[1] ou salmón chinook, Oncorhynchus tshawytscha,^[2] é un peixe osteíctio da familia dos salmónidos, subfamilia dos salmoninos, que se atopa nas áreas costeiras do océano Pacífico, entre California e o Xapón.

Animal eurihalino, vive no mar e migra remontando os ríos para reproducirse (anádromo).

É moi valorado pola súa relativa escaseza.

Descrición

Cardume de salmón real.

O adulto mide entre 84 e 147 cm de lonxitude e pesa entre 25 e 60 kg.

A marca de captura en pesca deportiva é de 44,1 kg, rexistrada polo pescador Les Anderson no río Kenai, Alasca, en 1985. Na pesca comercial o récord é de 57 kg, rexistrado preto de Petersburg, Alasca nunha captura en 1949.^[3]

É de cor azul verdosa sobre o lombo e a cabeza, prateada nos flancos e branca no ventre. Presenta puntos negros na cola e na parte superior do corpo; a súa boca é gris escura.

Reprodución

Pode pasar entre tres e cinco anos no océano antes de retornar polos ríos para procrear e desovar nas augas doces onde naceron. Prefire correntes máis grandes e profundas que outras especies de salmón; a desova ocorre entre setembro e decembro.

Unha vez nas partes altas da corrente de auga doce, a femia elixe o macho co cal se reproducirá. A súa selección baséase nas dimensións físicas do macho. A femia elixe unha zona da cama do río na cal haxa grava en abundancia e alí cava un burato pouco profundo coa cola, mentres que o macho danza fronte ela e fai vibrar o seu corpo. O número de ovos de oscilan entre os 3 mil e 14 mil segundo o tamaño da femia, e o macho fertilízaos subitamente cando ela os deposita.

Ambos os pais morren tras reproducírense. De acordo coa temperatura da auga, os ovos incúbanse entre 90 e 150 días antes de nacer as crías. Despois de 12 a 18 meses os exemplares xuvenís comezan a súa migración cara ao mar.

Cambios no corpo

Durante o período da reprodución sofre algunhas transformacións morfolóxicas. Ambos os dous sexos adquiren durante este tempo unha tonalidade avermellada rechamante sobre os flancos, máis intensa nos machos, que sofren mesmo a modificación nas costas, que se elevan, e da mandíbula inferior, que curva cara a arriba e impide que a boca se peche. Este crecemento da mandíbula volve practicamente imposible que os adultos poidan alimentarse durante a fase da reprodución, de xeito que dende que empezan a súa migración estacional cara ás fontes dos ríos para reproducírense manteñen un xaxún absoluto.

Distribución

Pesca deportiva de salmón.

Distribúese dende a baía de San Francisco en California cara ao norte seguindo a costa pacífica dos Estados Unidos, Canadá e Alasca, o estreito de Bering e o mar de Chukchi, o nororiente de Siberia, Rusia, a península de Kamchatka, as Illas Kuriles e as illas do Xapón.

En 1967 o Departamento de Recursos Naturais de Míchigan soltou salmóns reais no lago Michigan e no lago Huron para controlar a Alosa pseudoharengus unha especie invasora procedente do océano Atlántico. Despois de culminar con éxito esta implantación os salmóns reais foron levados a outros dos Grandes Lagos,^[4] onde son apreciados para a pesca deportiva.

A especie introduciuse nas costas da Patagonia chilena e arxentina, onde colonizou ríos e estableceu lugares estables de desova. Tamén foi levada con éxito a Nova Zelandia.^[5]

O río Yukón rexistra a máis longa ruta de migración do salmón, de máis de 3.000 km, dende o mar de Bering até as fontes preto de Whitehorse. Construíuse unha canle na presa hidroeléctrica do lago Schwatka para garantir o paso e a reprodución do salmón real en Whitehorse.

Ecoloxía

O salmón real necesita para sobrevivir:

1. alimento,
2. hábitat de desova,
3. hábitat oceánico,
4. augas frías, limpas e con osíxeno suficiente, e
5. outros salmóns

Toma do plancto para a súa alimentación diatomeas, copépodos, laminariais e macroalgas; ademais consome medusas, estrelas de mar, insectos, anfipódos, e outros crustáceos; e cando é adulto aliméntase tamén doutros peixes.

As augas limpas son esenciais para a desova. A vexetación ribeirega axuda a manter as condicións das augas para a reprodución e a vida xuvenil do salmón real.

Algunhas poboacións de salmón dos Estados Unidos están na lista de especies ameazadas, por exemplo a do Val Central de California. En abril de 2008 tanto en Oregón como en California debeu cancelarse a tempada de pesca debido á baixa poboación rexistrada. No río Sacramento a poboación da especie está ao bordo do colapso.^[6]

Na cultura

O salmón real é espiritual e culturalmente moi prezado polos pobos indíxenas amerindios das rexións onde habita orixinalmente, que celebran «cerimonias do salmón» na primavera. Foi descrito e ademais consumido con entusiasmo pola expedición de Lewis e Clark (1804-06). A importancia económica para as comunidades indíxenas e para outras poboacións é moi grande. É apreciado pola súa cor, sabor, textura e alto contido de aceites Omega-3.^[7]

Notas

Véxase tamén

Bibliografía

• 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.
• Lahuerta, F. e Vázquez, F. X. (2000): Vocabulario multilingüe de organismos acuáticos. Santiago de Compostela: Xunta de Galicia. ISBN 84-453-2913-8.
• Montgomery, David. King of Fish: The Thousand-Year Run of Salmon. Boulder, CO: Westview Press, 2003.

Outros artigos

• Salmónidos
• Salmoninos

Kraljevski losos (Oncorhynchus tshawytscha), riba iz porodice lososa ili pastrvki (Salmonidae) rasprostranjena na Pacifiku, u engleskom jeziku poznata kao kraljevski losos. Mrijesti u rijekama na pacifičkoj obali Amerike, sve od Point Hope, Aljaska pa do riijeke Ventura River u Kaliforniji, SAD, kao i na poluotoku kamčatka. Ova riba može narasti do 150 cmm ali joj je uobičakjena dužina 70. cm, a može dosegnuti težinu od preko 60 kg (rekordno je zabilježena težina od 61.4 kg.)

O. tshawytscha je veoma značajna u prehrani indijanskog stanovništva sa Sjeverozapadnog obalnog područja^[1], a plemena su imala svoja ribolovna područja, a njezina pojava izazivala je pokrete čitavog stanovništva.

O. tshawytscha je poznata zbog svog značaja pod brojnim nazivima, među kojima su globalni FAO nazivi Chinook salmon i King salmon, a kako se mrijesti i na poluotoku Kamčatka u Rusiji i tamo je poznata kao čaviča (чавыча)^[2], koji je i postao znanstveni naziv za ovu vrstu.

Izvori

• San Tomas Aquino Creek, 1996

• 1910. godina Astoria, Oregon

• 
• par kraljevskih lososa

Kóngalax (fræðiheiti: Oncorhynchus tshawytscha) er stærsta tegundin í ættbálki laxfiska.

Útbreiðsla

Hann lifir við strendur Norður–Kyrrahafs og dreifist um stórt svæði, í Austur–Kyrrahafi allt frá Ventura-ánni í Kaliforníu norður til Point Hope í Norður–Alaska og í Vestur–Kyrrahafi frá Hokkaido-eyju í Japan og norður til Anadyr-fljóts í Rússlandi. Nú er tegundin reyndar horfin af stórum svæðum þar sem hún var algeng áður fyrr en það á þó aðallega við um svæði í Norður–Ameríku. Einkum er það átroðningur manna sem hefur valdið því að laxinn hefur þurft að yfirgefa fyrri heimkynni, aðallega vegna þess að byggðar hafa verið stíflur sem hafa eyðilagt búsvæði hans. ^[1].

Útlit

Kóngalaxinn getur orðið allt að einn og hálfur metri að lengd en algeng lengd hans er um 80 sentimetrar. Þyngsti kóngalax sem veiðst hefur vó um það bil 61 kíló. Það er þó ekki algeng þyngd en vanalegt er að laxinn fari yfir 18 kíló. Útlit hans er breytilegt eftir því hvar hann er hverju sinni. Þegar hann er í sjó er hann blágrænn á bakið með silfraðar síður, litlar svartar doppur á sporði og baki og svartan neðri góm. Þegar laxinn snýr svo aftur úr sjónum og upp í ár til þess að fjölga sér verður hann brúnn eða rauður á lit. Litabreytingin verður mun meiri hjá hængnum en hrygnunni, kjaftur hængsins verður króklaga og bak hans verður kúpt. Kóngalaxinn er rauður á fiskinn en ekki bleikur eins og aðrir laxar, holdið getur þó stundum verið hvítt sem er sjaldgæft en það bragðast alveg eins og það rauða ^[2].

Lífsferill og lifnaðarhættir

Til eru tvær gerðir af kóngalaxi, annars vegar er það hin svokallaða straumlax og hins vegar sjólax. Munurinn á þeim er ekki ýkja mikill en hann felst í því að straumlaxinn er lengur í ánum en sjólaxinn eftir að hann klekst úr eggi. Sjólaxinn kemur oftast í lok sumars og í byrjun hausts upp í árnar til þess að hrygna, þeir koma þó á öllum tíma árs þó svo að þessi tími sé algengastur, en straumlaxinn kemur mest á vorin og í byrjun sumars. Þetta hegðunarmynstur má rekja til þess að flóð og þurrkar eru algengari í suðurhluta Bandaríkjanna og því er sjólaxinn aðallega að finna þar á meðan straumlaxinn heldur til norðar þar sem hann getur dvalið lengur í ánum eftir að hann hefur klakist úr eggi^[3]

Lífsferill hópanna er sams konar, ef undan er skilinn tíminn sem þeir dvelja í ánum í upphafi ævinnar. Eftir að hafa eytt byrjun ævi sinnar í ám (allt frá þremur mánuðum og upp í tvö ár), færa kóngalaxar sig á haf út þar sem þeir eru við fæðunám. Þeir halda sig samt að mestu nálægt ströndinni þótt vitað sé um fiska sem hafa farið allt að 1600 km frá landi. Meginuppistaða í fæðu kóngalaxins þegar að hann er ungur eru krabbadýr og vatna- og þurrlendisskordýr. Þegar laxinn stækkar og eldist nærist hann aðallega á öðrum fiskum eins og til dæmis lýsu og makríl. Þegar laxinn hefur náð að stækka og dafna í hafinu, snýr hann aftur upp í ána þar sem hann klaktist úr eggi til þess að fjölga sér. Algengast er að þetta gerist þegar að hann hefur verið í hafinu í um það bil tvö til fjögur ár en allt veltur þetta á því hvenær hver fiskur verður kynþroska (það getur verið allt frá tveggja ára aldri til sjö ára aldurs). Þegar hrygnan hefur fundið stað í ánni til þess að hrygna grefur hún nokkrar holur sem hún hrygnir svo í en hver hrygna getur hrygnt frá 3.000 til 14.000 eggjum. Þegar hrygnan hefur hrygnt eggjum sínum, gætir hún þeirra þar til hún drepst, hængurinn fer og finnur næstu hrygnu en að lokinni hrygningartíð drepst hann líka^[4].

Hængur á hrygningartímabili

Stjórnun veiða

NOAA Fisheries, Pacific and North Pacific Fishery Management Councils, og Alaska Department of Fish and Game eru þær stofnanir sem halda mest utan um veiðar á kóngalaxi í heiminum. Þessar stofnanir fara yfir veiðitölur síðasta fiskveiðiárs og í samræmi við þær og með tilliti til stofnstærðar gefa þær út kvóta á laxinn. Markmið þeirra er að leyfa veiðimönnum að veiða eins mikið og mögulega er án þess að skaða stofninn með ofveiði, ásamt því að stuðla að því að þeir stofnar sem eru í lágmarki á ákveðnum svæðum geti fengið að dafna á ný með því að minnka veiðar á þeim svæðum. Stofnanirnar meta hversu mikill hrygningarfiskur þarf að komast af til þess að stofnstærðin viðhaldist og því er það einnig tekið með inn í reikninginn þegar kvótanum er úthlutað ^[5].

Veiðar og markaður

3 stærstu veiðiþjóðir heims á kóngalaxi frá 1950-2010 samkvæmt FAO

Eins og fyrr segir lifir kóngalaxinn í Kyrrahafi og þær þjóðir sem hafa stundað mestar veiðar á honum frá árinu 1950 eru Bandaríkin, Rússland og Kanada en Bandaríkin hafa veitt meira en tvöfalt meira en Kanada og Rússland til samans. Veiðarnar hafa verið að dragast saman á undanförnum áratugum. Helstu aðferðirnar sem notaðar eru við veiðar á kóngalaxi eru veiðar í nót, lagnet og línuveiðar með beitu sem lokkar fiskinn að önglinum. Síðastnefnda aðferðin gefur mestu vörugæðin, því fiskurinn er þá tekinn lifandi og unninn ferskur úr sjó. Einnig eru stangveiðar stundaðar af áhugamönnum. Allt eru þetta veiðarfæri sem valda ekki skaða á heimkynnum laxins og annarra lífvera á þeim stöðum sem laxinn heldur sig. Meðafli er mjög lítill og þá aðallega aðrar laxategundir. Kóngalaxinn er veiddur að mestu leyti yfir sumartímann. Á síðasta ári (2012) var gefinn út kvóti upp á 266.800 fiska þar sem að 70% kvótans mátti veiða yfir sumartímann. Kvótanum var svo skipt niður eftir veiðarfærum með eftirfarandi hætti, 4,3% af kvótanum mátti veiða með nót, 2,9% í net, 80% á beitta línu og um það bil 13% á stöng. Langmestur hluti aflans af kóngalaxi veiðist við Suðaustur–Alaska en árið 2010 veiddust þar 262 þúsund laxar.^[6]

Árið 2010 var meðalverð á kíló af kóngalaxi upp úr sjó um það bil 942 íslenskar krónur, miðað við gengi á þeim tíma. Neytendur sækjast mjög eftir kóngalaxinum vegna þess hversu ríkur hann er af omega-3-fitusýrum, B12 vítamíni og próteinum. Hann er einnig feitari á fiskinn en aðrir laxar og þar með mýkri. Kóngalaxinn er seldur ferskur, frosinn, reyktur og niðursoðinn. Veiðarnar eru sjálfbærar og fyrir vikið er varan eftirsóttari. Helsti markaður fyrir kóngalax er Norður-Ameríka en mikill meiri hluti af þeim laxi sem er veiddur er seldur þangað.^[7]

Tilvísanir

1. ↑ Myers, J. M., Kope, R. G., Bryant, G. J., o.fl. (Febrúar, 1998). National Marine Fisheries Service Úttekt. Sótt 22 janúar 2013 af http://www.fws.gov/yreka/HydroDocs/Myers_etal_1998.pdf
2. ↑ NOAA Fisheries. (2013). Chinook Salmon(Oncorhynchus tshawytscha). Sótt 27. janúar 2013 af http://www.nmfs.noaa.gov/pr/species/fish/chinooksalmon.htm#distribution
3. ↑ NOAA Fisheries, 2013.
4. ↑ NOAA Fish Watch. (e.d.). Chinook Salmon. Sótt 27. janúar 2013 af http://www.fishwatch.gov/seafood_profiles/species/salmon/species_pages/chinook_salmon.htm
5. ↑ NOAA Fish Watch. (e.d.). Chinook Salmon. Sótt 03. febrúar 2013 af http://www.fishwatch.gov/seafood_profiles/species/salmon/species_pages/chinook_salmon.htm
6. ↑ NOAA Fish Watch. (e.d.). Chinook Salmon. Sótt 03. febrúar 2013 af http://www.fishwatch.gov/seafood_profiles/species/salmon/species_pages/chinook_salmon.htm
7. ↑ Welch, Laine. (2011). Strong prices for iconic chinook salmon so far in Southeast. Sótt 5. febrúar 2013 af http://classic.Alaskajournal.com/stories/051311/fis_spfics.shtml

Wikiorðabókin er með skilgreiningu á orðinu

Kóngalax

Wikimedia Commons er með margmiðlunarefni sem tengist

Kóngalax

Oncorhynchus tshawytscha (Walbaum, 1792), conosciuto comunemente come salmone reale^[1], è una specie di pesce osseo marino e d'acqua dolce appartenente alla famiglia Salmonidae.

Distribuzione e habitat

Il suo areale comprende l'Oceano Pacifico settentrionale. Lungo le coste americane è presente dall'Alaska alla California (a sud fino a San Diego). Sul lato asiatico dell'oceano è presente in Giappone. Si può incontrare nel mar del Giappone, nel mar di Bering e nel mar di Okhotsk^[2]. È stato introdotto nei Grandi Laghi e in alcune zone della Nuova Zelanda, dell'Australia, dell'Argentina e del Cile^[3]. Come tutti i salmoni è una specie anadroma che passa gran parte della vita in mare ed effettua migrazioni riproduttive verso il tratto alto dei fiumi dove avviene la deposizione delle uova nello stesso torrente natale. Alcuni individui si accrescono nei laghi anziché in mare. I giovanili di solito scendono in mare a un anno di età ma talvolta dopo solo 3 mesi o dopo addirittura 3 anni. In mare ha abitudini epipelagiche anche se pare che possa spingersi fino a 375 metri di profondità^[2].

Descrizione

L'aspetto di questo pesce durante la vita marina è simile a quello degli altri salmoni ma ha corpo più alto e compresso, specialmente negli individui di taglia maggiore. Il maschio riproduttivo ha dorso gibboso e mascelle incurvate. Si distingue dagli altri salmoni del Pacifico in fase marina per i piccoli punti neri che ricoprono il dorso ed entrambi i lobi della pinna caudale e per avere gengive nere nella mascella inferiore. Il dorso e la testa sono di colore da verde cupo a blu, i fianchi argentei e il ventre biancastro. La livrea riproduttiva è variabile, di solito ha toni brunastri, rossicci o rosei, molto più marcati negli individui maschili^[2].

Può raggiungere i 150 cm di lunghezza, con una taglia media compresa tra i 60 e 90 cm. Il peso massimo noto è di 61.4 kg^[2].

Biologia

Vive fino a 9 anni^[2].

Alimentazione

I giovanili in acqua dolce catturano in prevalenza insetti e piccoli crostacei. In mare si ciba soprattutto di pesci e crostacei^[2].

Riproduzione

La migrazione riproduttiva inizia in inverno e può raggiungere una distanza massima di 4.827 km dal mare. La femmina prepara un nido scavando una buca sul fondale dopo di che viene affiancata dal maschio dominante più vicino, seguito da alcuni altri maschi non dominanti che si pongono nelle immediate vicinanze. Il maschio tocca la pinna dorsale della femmina per stimolarla. I riproduttori muoiono pochi giorni dopo la riproduzione^[2].

Pesca

Questo salmone è molto importante per la pesca commerciale (che lo insidia con reti a strascico e reti da posta) e per la pesca sportiva. Gli stati che catturano le maggiori quantità sono Stati Uniti e Russia. La carne è ottima, in gran parte degli esemplari ha colore rosso ma talvolta è bianca^[2][4]. Le marinerie dell'Alaska che pescano questa specie hanno ricevuto la certificazione di sostenibilità e di buona gestione degli stock del Marine Stewardship Council^[5].

Note

De chinookzalm of quinnat^[1] (Oncorhynchus tshawytscha; afgeleid van het Russische чавыча; 'tsjavytsja'), een beenvis is de grootste van de Pacifische zalmen. De vis staat bij de Amerikanen ook bekend als koningszalm, springzalm en ettelijke andere namen. De vis kan een lengte bereiken van 150 cm en het hengelrecord was een exemplaar van 57 kg. Hij wordt bij de hengelaars beschouwd als een goede vechter en eetbare vis. De gebruikelijke gewichten liggen tussen de 9 (twee jaar op zee) en de 30 (5 à 6 jaar op zee) kg. De leeftijd van de paaiende vissen varieert van 2 tot 7 jaar. De hoogst geregistreerde leeftijd is 9 jaar.

Verspreiding

Het verspreidingsgebied loopt van de Baai van San Francisco tot de Tsjoektsjenzee in Rusland. Ze komen op onregelmatige basis voor in noordelijke Pacifische kustwateren.

Chinooks zijn ook met succes uitgezet in Zuid-Amerika, met name Zuid-Chili, in de Grote Meren op de grens van de VS en Canada en in Nieuw-Zeeland.

Herkenning

Winterchinookzalm

De chinookzalm is een goed geproportioneerde, gestroomlijnde vis, zilverachtig aan de zijkanten en met een donkere rug. Zwarte vlekjes lopen van achter de kieuwdeksel via de rug tot aan het staartgedeelte. Ook op de rugvin en staartvin komen zwarte vlekjes voor. De chinook is relatief grofbeschubd. De flanken zijn in de winter voorzien van een purperachtig zweem, dat in de zomer zwart wordt. Een onmiskenbaar kenmerk van de chinookzalm is het zwarte tandvlees. De bek is voorzien van goed ontwikkelde scherpe tanden. Aan de vissige okselgeur kan de vis ook prima herkend worden.

Leefomgeving en levenswijze

De chinookzalm blijft vaak in de buurt van de kust, afhankelijk van de breedtegraad kan er gedurende een bepaald gedeelte van het jaar langs de kust op chinook gevist worden. Hij zoekt wel gedurende een bepaalde tijd de noordelijke gedeelten van het verpreidingsgebied om op te groeien. Hij is vaak te vinden in losse scholen bij bijzondere structuren langs de kust, zoals onderwaterbergen, riffen, zandbanken en kuilen.

Op een bepaalde plaats langs de kust kan zowel zomer- als winterchinook voorkomen. De winterchinooks zijn vissen die ook in de winter langs deze kust blijven en de zomerchinook trekken in het zomerseizoen vlak langs de kust op weg naar hun paairivieren. De trekkende vissen in de zomer zijn voor hengelaars het interessantst omdat ze vlak langs de kust op niet al te grote diepte kunnen worden gevangen. De lokale zalmen blijven ook in de zomer op grote diepte, zodat in de zomer de scholen ruimtelijk gescheiden blijven doordat de zomervorm tientallen meters boven de wintervorm uitzwemt.

Het is opvallend dat in veel streken de trekkende chinookzalm niet verder dan 100 meter uit de kust komt. Het is ook een vis die licht mijdt, zodat hij overdag op dieptes van 60 tot 80 meter voorkomt, maar 's ochtends vroeg wel op dieptes van minder dan een meter gezien wordt. Over het algemeen bevindt hij zich op waterdieptes van circa 15 meter. 's Winters wordt hij gevangen op dieptes van 30 tot 80 meter.

De chinookzalm zoekt ook scholen op van de favoriete prooien als haring en pijlinktvis. De chinook is een typische viseter, vandaar de scherpe tanden en de snelle groei.

Relatie tot de mens

De chinookzalm is voor de visserij van groot commercieel belang. Het visvlees heeft noch een flauwe, noch een zeer uitgesproken smaak. Vis die in de winter wordt gevangen, heeft wat meer vet, zodat deze voor de keuken geprefereerd wordt.

Voor de hengelsport is dit ook een zeer gewilde soort vanwege het grote formaat. De zalmen zijn ontzettend krachtig, maar leveren minder spektakel in de vorm van sprongen en dergelijke dan de coho zalm.

Ze zijn goed te vangen met visimitaties of met dode of levende vis. Omdat de vis niet al te ver uit de kust zwemt, is ze ook goed te bereiken vanaf de kust of kleine bootjes. Tijdens de voor- of najaarsruns zijn ze op rivieren ook aan de vliegenhengel te vangen.

In de Yukonrivier vindt jaarlijks de langste trek plaats, sommige vissen leggen ruim 3000 kilometer af. Sedert 1958 werd nabij Whitehorse een hydro-elektrische dam gebouwd, waardoor de vissen (net als de rivierforel) hun paaigronden niet meer konden bereiken. Daarop werd de grootste visladder ter wereld gebouwd.

Externe link

• Foto's van de chinook zalm op FishBase

• Froese, R., D. Pauly. en redactie. 2005. FishBase. Elektronische publicatie. www.fishbase.org, versie 06/2005.
• Reid, D.C. 1996? A fisherman looks at Chinook salmon

[1] [2]

Zie de categorie Oncorhynchus tshawytscha van Wikimedia Commons voor mediabestanden over dit onderwerp.

1. ↑ Grzimek, B. et al. (1972). Het leven der dieren: Deel IV Vissen I. Uitgeverij Het Spectrum N.V., Utrecht/Antwerpen. ISBN 9789027486240

Czawycza^[2] (Oncorhynchus tshawytscha) – gatunek morskiej ryby z rodziny łososiowatych (Salmonidae). Największy przedstawiciel rodzaju Oncorhynchus.

W Rosji nazywana carycą łososiowatych, w Ameryce Północnej nazywana king salmon – łosoś królewski.

Występowanie

Ryba dwuśrodowiskowa. Występuje w zlewiskach północnego Oceanu Spokojnego, Oceanie Arktycznym, morzu Ochockim, na wybrzeżach Kuryli i Aleutów oraz w zatoce Alaska, czasami również u wybrzeży San Diego. Po azjatyckiej stronie Pacyfiku liczebność jest mniejsza . Słynie z pokonywania dużych odległości z morza w górę rzek w celu odbycia tarła. Popularna na Kamczatce, na Alasce obserwowana w Jeziorze Bennetta – ok. 4000 km rzeką Jukon.

W 1989 w Polsce podjęto nieudaną próbę introdukcji tego gatunku.^[3]

Opis

Czawycza tak jak pozostałe z rodziny z Salmonidae, ma wydłużone, dobrze umięśnione ciało, lekko spłaszczone po bokach. Przeciętne wymiary wynoszą 70-90 cm, ale osiąga długość do 150 cm, natomiast ciężar 15-20 kg przy maksymalnej masie ciała 61,4 kg^[4]. Czawycze przebywające w morzu mają ubarwienie srebrne z ciemnozielonym grzbietem. W okresie godowym, gdy wstępują do rzek ich skóra ciemnieje do koloru oliwkowobrązowego, czerwonego lub purpurowego – zwłaszcza u samców. Posiada także dobrze rozwinięta linie naboczną.

Płetwa tłuszczowa jest umiejscowiona na grzbiecie za płetwą grzbietową. Płetwy piersiowe znajdują się poniżej głowy. Płetwę brzuszną charakteryzuje poprzedzający fałd mięso-skórny. W dużym otworze gębowym zęby są osadzone na szczękach oraz na podniebieniu, natomiast dziąsła są czarne.

Odżywianie

Młode żywią się larwami owadów, a dorosłe bezkręgowcami i rybami.

Rozród

Czawycza

Tarło odbywa się w górnym biegu rzek. Młode pozostają w wodach słodkich od trzech miesięcy do roku, rzadziej do trzech lat, po czym spływają do morza. Rozród odbywa się w ciągu całego roku – głównie od wiosny do lata. Czawycza podczas godów traci mniej tłuszczu niż pozostałe gatunki. Wędrówka narybku trwa 1–2 lata. Istnieją również formy rzeczno-jeziorne o mniejszych rozmiarach. Pod względem zachowania można wyróżnić dwie formy: typ potokowy i typ oceaniczny. Pierwszy z nich, typowy dla populacji Azji, zostaje na rok lub dłużej w wodzie słodkiej zanim wyruszy do morza. Wraca do rzeki na wiosnę lub latem. Część męskiego narybku typu potokowego nigdy wypływa do wód morskich. Natomiast typ oceaniczny jest charakterystyczny dla południowego wybrzeża Ameryki Północnej. Typ ten wypływa do morza zwykle w 3 miesiącu życia. Do rzeki wraca na jesień Podczas wędrówki ryba znajduje drogę posługując się kątem podania światła, kierunkiem pływów morskich, węchem, a także światłem spolaryzowanym.

Znaczenie w ochronie środowiska

W amerykańskiej ustawie o zagrożonych gatunkach Endangered Species Act nadany jej został status "zagrożony". Zmniejszająca się populacja łososia, wpływa negatywnie na populacje orek, dla których łosoś stanowi podstawę pożywienia.^[5]

W roku 1989 została podjęta introdukcja czawyczy w śródlądowych wodach Polski, zakończona niepowodzeniem.

Znaczenie gospodarcze

Poławiane są na dużą skalę w celach konsumpcyjnych ze względu na ich wartościowy kawior i niezwykłe walory smakowe mięsa. Odgrywają dużą rolę w gospodarce Alaski, gdzie są łowione i następnie eksportowane w postaci konserw. W akwakulturach hodowane są głównie w Nowej Zelandii. Największymi importerami są Japonia i inne kraje zachodniej części Oceanu Spokojnego.

Aktualne kierunki badań naukowych

Czawycza jest rybą dwuśrodowiskową, dlatego też jest doskonałym obiektem badań dotyczących wędrówek i rozrodu. Jest również badana pod kątem wpływu substancji chemicznych na ten gatunek tj. diazinon powodujący zaburzenia w zachowaniach służących obronie oraz w zakresie genetyki.

Przypisy

Bibliografia

• Włodzimierz Załachowski: Ryby. Warszawa: Wydawnictwo Naukowe PWN, 1997. ISBN 83-01-12286-2.
• Burger C.V., Wilmot R.L., Wangaard D.B., Comparison of Spawning Areas and Times for Two Runs of Chinook Salmon (Oncorhynchus tshawytscha) in the Kenai River, Alaska, „Canadian Journal of Fisheries and Aquatic Sciences”, 42 (4), 1985, s. 693–700, DOI: 10.1139/f85-089 [dostęp 2017-03-20].
• Cihař J., 1992 .Przewodnik Ryby Słodkowodne. Multico. Warszawa.
• Fishbase, 2016. http://www.fishbase.org/Photos/PicturesSummary.phpStartRow=2&ID=244&what=species&TotRec=15
• Groot C., Margolis L. 1991. Pacific Salmon Life Histories. UBC Press. .
• Helfman G. S.,. Collette B.B., Facey D. E., Bowen B.W., 2010. The diversity of fishes. John Wiley & Sons, Inc. New York.
• Paxton J.R., Eschmeyer W.N., 1994. Encyklopedia zwierząt Ryby. Agencja Elipsa. Warszawa.
• Rutkowicz S., 1982. Encyklopedia ryb morskich. Wydawnictwo morskie Gdańsk. Gdańsk.
• Scholz N.L. i inni, Diazinon disrupts antipredator and homing behaviors in chinook salmon (Oncorhynchus tshawytscha), „Canadian Journal of Fisheries and Aquatic Sciences”, 57 (9), 2000, s. 1911–1918, DOI: 10.1139/f00-147 [dostęp 2017-03-21].

Oncorhynchus tshawytscha (em inglês: Chinook salmon, em português também conhecido por Rei Salmão ou Salmão-Rei) é um peixe da família Salmonidae. Pode ser encontrado em águas costeiras do Pacífico Norte, da Califórnia ao Japão.

Características

Na idade adulta o “Chinook” pode chegar a medir entre 84 e 147 cm de longitude e pesar entre 25 e 60 kg.

Cor

O salmão “Chinook” se caracteriza por ser de cor azul esverdeado na parte superior do lombo e na cabeça, prateado nos lados e branco no ventre. Assim mesmo possui manchas negras no rabo e na parte superior do seu corpo.

Durante o período de reprodução esta espécie sofre transformações no seu corpo, colorindo-se de cor avermelhada nas suas extremidades, o qual se intensifica ainda mais nos machos. Ademais a estas mudanças, o “Chinook” sofre modificação em suas costas, a qual se eleva e sua mandíbula se curva impedindo a este peixe fechar a boca e, como consequência, alimentar-se.

Alimentação

A alimentação do “Chinook” se compõe de medusas, estrelas-do-mar, insetos, anfípodes e outros crustáceos.

Igual a outros peixes da mesma família, o “Chinook” ao chegar na idade adulta também incorpora entre seus alimentos outros peixes de menor tamanho.

Habitat

No Chile o “Chinook” foi introduzido se estabeleceu nos rios da região sul, como o Petrohué e o Hueño Hueño, aos quais chegam a cada temporada a produzir sua desova e morrer. Também foi introduzido na Patagônia e Nova Zelândia^[1].

Referências

Kungslax (Oncorhynchus tshawytscha)^[3] är en fiskart som först beskrevs av Johann Julius Walbaum 1792. Kungslax ingår i släktet Oncorhynchus och familjen laxfiskar.^[5][6][7] Arten har ej påträffats i Sverige.^[7] Inga underarter finns listade i Catalogue of Life.^[5]

Det vetenskapliga namnet för släktet är sammansatt av de grekiska orden för nagel och nos/tryne. Artepitet är trivialnamnet för fisken i Kamtjatka.^[6]

Utbredning

Arten förekommer i norra Stilla havet och i angränsande bihav. För att fortplanta sig simmar den upp i angränsande floder i östra Ryssland, Japan (Hokkaido) och Nordamerika (från Kalifornien till Alaska).^[8]

Kungslaxen introducerades bland annat vid de Stora sjöarna i USA och i Nya Zeeland.^[8] Där arten inte är inhemsk påverkar den ekosystemet ofta negativt.^[6]

Utseende

Kungslaxen blir vanligen 91,4 cm lång och 13,6 kg tung. Stora exemplar når en längd av upp till 147,3 cm och en vikt av 61,4 kg. Utanför parningstiden har arten en blågrön rygg, silver färgade kroppssidor och en vitaktig buk. På ovansidan och på fenorna förekommer många svarta fläckar. Under parningstiden utvecklas hos båda kön en röd skugga på kroppen som är tydligast hos hanarna.^[8]

Ungar har en avvikande färgsättning med flera mörka ovala och upprätt stående märken på bålens sidor.^[8]

Ekologi

Arten vistas i havet nära kusten eller den simmar till djupa regioner utanför fastlandssockeln. Liksom flera andra laxfiskar simmar kungslaxen till vattendraget där den föddes. Det är snabb flyttande floder eller bäckar med en vattentemperatur av 14 °C eller kallare.^[8]

Unga kungslaxar äter plankton, vattenlevande insekter, grodyngel och kräftdjur. I havet utgörs födan av olika mindre fiskar, bläckfiskar, kräftdjur och annan zooplankton. Vuxna individer som vandrar till sina fortplantningsområden fastar.^[8]

Källor

1. ^ [a b c d e f g h] Scott, W.B. and E.J. Crossman (1973) Freshwater fishes of Canada., Bull. Fish. Res. Board Can. 184:1-966.
2. ^ [a b c] Eschmeyer, W.N. (ed.) (1998) Catalog of fishes., Special Publication, California Academy of Sciences, San Francisco. 3 vols. 2905 p.
3. ^ [a b] Page, L.M. and B.M. Burr (1991) A field guide to freshwater fishes of North America north of Mexico., Houghton Mifflin Company, Boston. 432 p.
4. ^ Berg, L.S. (1962) Freshwater fishes of the U.S.S.R. and adjacent countries. volume 1, 4th edition., Israel Program for Scientific Translations Ltd, Jerusalem. (Russian version published 1948).
5. ^ [a b] Bisby F.A., Roskov Y.R., Orrell T.M., Nicolson D., Paglinawan L.E., Bailly N., Kirk P.M., Bourgoin T., Baillargeon G., Ouvrard D. (red.) (14 april 2011). ”Species 2000 & ITIS Catalogue of Life: 2011 Annual Checklist.”. Species 2000: Reading, UK. http://www.catalogueoflife.org/annual-checklist/2011/search/all/key/oncorhynchus+tshawytscha/match/1. Läst 24 september 2012.
6. ^ [a b c] FishBase. Froese R. & Pauly D. (eds), 2011-06-14, Oncorhynchus tshawytscha
7. ^ [a b] Dyntaxa Oncorhynchus tshawytscha
8. ^ [a b c d e f] Caren Scott (14 april 2003). ”Blackmouth” (på engelska). Animal Diversity Web. University of Michigan. http://animaldiversity.org/accounts/Oncorhynchus_tshawytscha/. Läst 8 juni 2016.

Externa länkar

• Wikimedia Commons har media som rör Kungslax.
  Bilder & media
• Wikispecies har information om Oncorhynchus tshawytscha.
  Artförteckning

Denna fiskrelaterade artikel saknar väsentlig information. Du kan hjälpa till genom att tillföra sådan.

Kral sombalığı (Oncorhynchus nerka), alabalıkgiller (Salmonidae) familyasından anodrom deniz balığı türü.

Morfoloji

Sırtı mavi-yeşil, kırmızı ya da mor, başın üstü gümüş kenarlı ve ventralde beyazdır. Kuyruk ve vücudun üst yarısında siyah lekeler görülür. Ağzı genelde koyu mordan siyaha kadar değişkendir. Erginleri 610 ilâ 910 mm olsa da 1.500 mm ye ulaşan örnekleri de görülür. En sonki iri örneği 44.11 kg ile Alaska'da yakalanmıştır.

Yayılımı

Büyük Okyanusun kuzeyinde yaşar.

Див. також

• Горбуша
• Кета
• Кижуч
• Сима
• Пструг райдужний

Cá hồi Chinook (danh pháp hai phần: Oncorhynchus tshawytscha) là một loài cá di cư sống phần lớn thời gian ở biển, nhưng ngược dòng về sinh sản trong vùng nước ngọt, thuộc họ Salmonidae. Chúng là loài cá hồi Thái Bình Dương và được biết đến với nhiều tên gọi trong tiếng Anh như king salmon, tyee salmon, Columbia River salmon, black salmon, chub salmon, hook bill salmon, winter salmon, Spring Salmon, Quinnat Salmon và blackmouth. Cá hồi Chinook thường thường được chia thành các "chủng loại" như "chinook mùa xuân", "chinook mùa hè" và "chinook mùa thu" là các chủng loại phổ biến nhất. Các chủng loại này được xác định dựa theo thời gian cá hồi trưởng thành bơi vào vùng nước ngọt để sinh sản. Chủng cá hồi "chinook mùa đông" được ghi nhận tại sông Sacramento.

Cá hồi Chinook có giá trị cao vì chúng rất hiếm so với cá loài cá hồi Thái Bình Dương khác sống dọc phần lớn duyên hải Thái Bình Dương.

Hình dạng

Cá hồi Chinook có màu xanh lá-xanh dương trên lưng và trên đỉnh đầu với hai bên mình màu bạc và bụng màu trắng. Chúng có những điểm màu đen trên đuôi và phân nửa thân phía trước; miệng của chúng màu xám đậm. Cá trưởng thành có khổ dài từ 33 đến 36 in (840 đến 910 mm), nhưng có thể lên đến 58 in (1,47 mét); nặng từ 10 đến 50 cân Anh (4,54 đến 22,7 kg), nhưng có thể lên đến 130 cân Anh (59 kg). Kỷ lục câu cá hồi Chinook như môn thể thao là 97 cân Anh 4 ounce (44,1 kg). Nó được Les Anderson câu được vào tháng 5 năm 1985 trên sông Kenai (Kenai, Alaska). Kỷ lục thế giới đánh bắt thương mại là 126 cân Anh (57 kg) được đánh bắt gần Petersburg, Alaska năm 1949.^[1]

Sinh sản

Đàn cá hồi Chinook

Cá hồi Chinook có thể sống từ 1 đến 5 năm trong đại dương trước khi trở về những con sông quê hương của chúng để đẻ trứng. Cá hồi Chinook thích vùng nước sâu và rộng để đẻ trứng hơn những loài cá hồi khác. Chúng có thể được tìm thấy trong các ổ đẻ trứng từ tháng 9 đến tháng 12. Sau khi đẻ trứng trong ổ, cá cái Chinook sẽ giữ ổ từ 4 đến 25 ngày trước khi chúng chết trong lúc đó cá đực tìm con cá cái khác.

Trứng cá hồi Chinook sẽ nở, tùy theo nhiệt độ nước, từ 90 đến 150 ngày sau khi được đẻ ra. Trứng được đẻ vào một thời điểm thích hợp để cá hồi con có thể sinh tồn và phát triển. Cá con thường thường sống trong vùng nước ngọt từ 12 đến 18 tháng trước khi lội xuống các cửa sông gần biển, nơi chúng ở đó thêm vài tháng.

Chúng cũng biến màu thành đỏ sáng trước khi đẻ trứng. Chúng đẻ trứng trong những nhánh sông chính để tránh bị các loài thú khác ăn thịt.

Vòng đời đặc trưng của cá hồi Chinook Alaska là 4-5 năm. Tuy nhiên cũng có một số cá hồi Chinook quay trở về vùng nước ngọt sớm hơn những con cá hồi cùng lứa từ 1 đến 2 năm. Người ta thường gọi những con cá hồi trở về nước ngọt sớm hơn là cá hồi "Jack". Cá hồi "Jack" chỉ bằng phân nửa cá hồi Chinook trưởng thành.

Vùng sinh sống

Vùng sinh sống của cá hồi Chinook là từ vịnh San Francisco ở California đến phía bắc eo biển Bering ở Alaska, những vùng biển vùng Bắc cực của Canada và Nga (biển Chukotka (hay biển Chukchi) bao gồm toàn bộ duyên hải Thái Bình Dương ở giữa. Chúng cũng hiện diện ở châu Á, xa về phía nam đến quần đảo Nhật Bản. Ở Nga, chúng được tìm thấy tại Kamchatka và quần đảo Kuril.

Năm 1967, Bộ Tài nguyên Thiên nhiên Michigan có nuôi trồng loài cá hồi Chinook trong hồ Michigan và hồ Huron để kiểm soát sự phát triển của một loài cá trích có danh pháp Alosa pseudoharengus (ale-wife), một loài cá xâm hại sinh sản lan tràn, không được ưa chuộng, có xuất xứ từ Đại Tây Dương. Cá Ale-wife lúc đó chiếm 90% vùng sinh vật của các hồ. Cá hồi Coho cũng đã được nuôi trồng một năm về trước và chương trình đã thành công. Cá hồi Chinook và Coho phát triển mạnh hơn cá ale-wife và sử dụng các nhánh sông của các hồ này để đẻ trứng. Sau thành công này, cá hồi Chinook được nuôi trồng trong các hồ khác của Ngũ Đại Hồ,^[2] nơi chúng được đánh giá cao như là loài cá dành cho môn câu cá thể thao vì chúng rất hám mồi câu.

Loài cá này cũng đã sinh sôi nảy nở trong những vùng nước của vùng địa lý Patagonia ở Nam Mỹ. Nó được đưa sang nuôi thử tại các vùng nước ở New Zealand vào đầu thế kỷ 20 và đã thành công. Các nơi đẻ trứng là sông Rangitata, sông Opihi, sông Ashburton, sông Rakaia, sông Waimakariri, sông Hurunui, và sông Waiau.^[3] Trong khi các loài cá hồi khác cũng đuyược du nhập vào New Zealand thì chỉ có cá hồi Chinook (hay Quinnat theo tên gọi địa phương tại đây) là thiết lập được các đàn sống ngoài biển khơi có tầm quan trọng.

Sông Yukon là con đường di cư nước ngọt dài nhất của bất cứ cá hồi nào, dài trên 3.000 km từ cửa sông trong biển Bering đến nơi đẻ trứng trên thượng nguồn Whitehorse, Yukon. Một thang cá đã được xây dựng quanh đập thủy điện hồ Schwatka tại Whitehorse để cho cá hồi Chinook dễ dàng đi qua đập.

Trong văn hóa và thương mại

Được đoàn thám hiểm Lewis và Clark miêu tả và ăn nhiệt tình, cá hồi Chinook cũng được một vài bộ lạc thổ dân Bắc Mỹ đánh giá cao về mặt văn hóa và tinh thần. Nhiều bộ lạc kỷ niệm con cá hồi mùa xuân được đánh bắt đầu tiên mỗi năm bằng các "First Salmon Ceremony" (nghi lễ cá hồi đầu tiên). Trong khi đánh bắt cá hồi vẫn còn là quan trọng về mặt kinh tế cho nhiều cộng đồng bộ lạc thì thu hoạch cá hồi Chinook vẫn là có giá trị nhất.

Được biết đến như là "king salmon" (cá hồi vua) tại Alaska vì kích thước lớn và thịt đầy hương vị, cá hồi Chinook là cá biểu tượng của tiểu bang này. Những con cá hồi từ sông Copper ở Alaska được biết đến vì màu sắc, giàu hương vị, thịt chắc và chứa nhiều hàm lượng dầu Omega-3.^[4]

Chú thích

Tham khảo

• Oncorhynchus tshawytscha (TSN 161980) tại Hệ thống Thông tin Phân loại Tích hợp (ITIS). Truy cập ngày 30 tháng 1 năm 2006.
• Thông tin "Oncorhynchus tshawytscha" trên FishBase, chủ biên Ranier Froese và Daniel Pauly. Phiên bản tháng tháng 10 năm 2005.
• Cameron Mindy. Salmon Return; A Public Conversation About the Future of a Northwest Icon. The Seattle Times. [Seattle, WA]. 18 tháng 8 năm 2002.
• Christie Patrick. Bài giảng. 22-4-2005. Vashon-Maury Islands Case Study: Incompatible Desires? Growth and Maintaining Salmon Populations in Puget Sound. University of Washington; Seattle, WA.
• Klinger Terrie. Bài giảng. 15-4-2005. 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.

Liên kết ngoài

• 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
• Chinook Salmon News Archive
• Season/Timing information for King Salmon in the Great Lakes region
• The Tyee Club
• United Anglers of Casa Grande High School

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處於產卵期的帝王鮭

帝王鮭，又稱大鱗麻哈魚或音譯作切努克鮭魚，是麻哈魚屬的一種，為溫帶魚類，分布北太平洋區，從日本海、鄂霍次克海、阿拉斯加、白令海、加拿大淡水、半鹹水及海域，深度0-375公尺，體長可達150公分，棲息在表中層水域，會進行洄游，幼魚孵化後洄游回大海，以昆蟲、甲殼類為食，成魚為大洋性，以魚類、甲殼類等為食，成群活動，為海洋哺乳類、鳥類及大型魚類捕食，為高經濟價值食用魚，適合各種烹飪方式食用，另可做為養殖魚、遊釣魚及觀賞魚。

參考文献

• Froese, Rainer & Daniel Pauly, eds. (2015). Oncorhynchus tshawytscha in FishBase. 2015年10月版本

扩展阅读

「キングサーモン」はこの項目へ転送されています。アラスカ州の地域については「キングサーモン (アラスカ州)」をご覧ください。

マスノスケ （鱒の介、学名:Oncorhynchus tshawytscha）英: Chinook salmon）は、サケ目サケ科に属する魚。別名キングサーモン^[1]（英: King salmon）。

分布[編集]

サケ属中では最も冷水を好み、アラスカからカムチャツカ半島にかけての北太平洋を中心にオホーツク海、日本海北部などに分布するが、分布数はアラスカ沖の北太平洋に偏る。日本国内ではロシアに回帰する一部の個体が、主に北海道の太平洋沿岸で漁獲されるものの、数は多くない。尚、国内には恒常的な産卵場所となる河川は存在しないが、佐渡島や東北地方以北の河川で捕獲された例がある^[2]。

孵化後、海洋で1 - 5年ほど生活し、多くの個体は4 - 6年で成熟するが、オスでは、海洋生活が1年程度と考えられる小型早熟の個体が現れる。その後は産卵のため、再び生まれ育った川を目指して遡上する。また、アラスカユーコン川産の個体では、川に入ってから産卵場所となる上流にたどり着くまで、遡上する距離が1,000kmを超えるものも存在する。

寄生虫の分析により、アジア系、カムチャッカ系、アメリカ系の3系統の群れがいることが判明しており、各々の群れの生活様式（遡上から産卵・孵化、降海生活、回遊海域、遡上時期）は異なっている^[3]。

1900年代にアメリカからニュージーランドに移植され定着している。

別名[編集]

キングサーモン以外の別名にはスケ（介）・スケマス（介鱒）・オオスケ（大介）などがある。標準的な和名であるマスノスケやこれらの名称に含まれる「スケ」とは、国司の四等官のうち次官である介（すけ）を意味する。現地赴任する国司のうちの官位筆頭者で任国で強権を振るった受領は、東国の大国たる親王任国の上野国、常陸国、上総国では次官の介であり、普通のサケ（シロザケ）やマス（サクラマス）よりも巨大なこの種を、サケやマスの親分格の存在と見立て、国衙に君臨する介に例えたものである。北海道では大きく育ってほしいと願いを込めて男の子にオオスケ(オウスケ)と命名する文化がある。

鮮魚店などでは「キングサーモン」の名称で販売されていることが多いが、別種であるタイセイヨウサケ（アトランティックサーモン）も同じ「キングサーモン」の名前で並べられている場合も多い。

英語で「king-of-the-salmon」というのはキングサーモンとは全く異なり、学名「Trachipterus altivelis」という大きな深海魚である。

生態[編集]

釣り上げられたマスノスケのオス。
身体には婚姻色が表れている。

孵化・浮上後直ち(3ヶ月以内)に降海する個体群は「海洋型」に分類され、孵化後1年から2年をベニザケの様に淡水生活を行った後に降海する個体群は「河川型」分類される。生活史は型の個体群で大きく異なる。同一河川では海洋型よりも河川型の方が産卵時期が早い傾向がある。降海時期は共に、融雪水の増加する4月から6月。産卵期には、幅があり夏の集団と秋の集団が存在する。

• 海洋型（秋サケ）は、主にアラスカの北緯56度以南に生息し、沿岸を生息海域とし海洋での越冬はせず産卵直前に母川回帰する。数ヶ月間の海洋生活の後、7月から12月に遡上を開始し河川型ほど上流までは遡上せず中流から下流域で産卵する。
• 河川型（夏サケ）は、アジア系、カムチャッカ系とも呼ばれ、沖合を生息海域とし1 - 4回の海洋での越冬を行い、2月から7月に遡上を開始し、より上流まで遡上を行い産卵をする。産卵期は、秋から冬。カムチャツカ系の産卵期は7-8月。

いわゆるサケ科魚類の中では、北海道に生息するイトウと並んで大きさは最大級であるが（大きなものでは体長が1.47 m、体重は60 kg近くに達するものも存在する）、通常漁獲される個体は概ね体長80 - 90 cm、体重は5 - 20 kg程度である。体色は、背面は黒色点が散在する青緑色、腹部は銀白色をしている。尾鰭には銀色の放射条と黒色斑があることで他のサケ・マスと区別できる。また体に対する目の大きさも、他のサケ・マス類と比較してやや小さめである。

用途[編集]

本種はサケ類の中でも特に脂肪分が多く、美味とされる。国内で流通するものの多くはアラスカやロシアなどからの輸入もの（主に海中で養殖された個体）であり、日本産は少ない。主な用途は缶詰加工、塩漬けの切り身（焼き魚用）、燻製（スモークサーモン）、刺身など。また卵も他のサケ同様、イクラなどに加工される。

資源量[編集]

タイヘイヨウサケ属の魚はサケ（シロザケ）、ベニザケ、カラフトマスのような動物プランクトンを主に食べて育つ種と、サクラマス、ギンザケのように他の魚類を主に捕食する種に大別されるが、マスノスケは同属の中でも魚食性の代表格で、海域によって変化するが成魚はニシン、イカナゴ、イカなどを捕食する。食物連鎖の上で高位にあることもあり、プランクトン食のサケ類と比べて資源量ははるかに少ない^[4]。

1970年代には400万尾の漁獲量があったが、2000年頃には100万尾まで減少している。この間、沖合サケマス漁が資源減少の原因とされた為、公海上の沖合サケマス漁は1992年以降禁漁となったが、資源減少には歯止めが掛かっていない。つまり、資源減少の原因は海洋上での捕獲ではなく、遡上河川に建設されているダムが原因となり淡水生活が大きな影響を受けていると考えられるが、解明はされていない^[3]。この他、表面水温の変動の影響を強く受けている^[5]との調査結果もある。

日本国内での放流事業は1959年(昭和34年)以降、発眼卵を輸入し北海道内の河川に稚魚を放流している、1964年には十勝川及び日高沿岸で回帰した個体も捕獲された^[6]が、現在は行われていない。

遺伝子組み換えへの利用[編集]

バイオベンチャーのアクアバウンティ・テクノロジーズは、遺伝子組み換えサケ「アクアドバンテージ・サーモン; AquAdvantage salmon」を開発した。このサケは、アトランティックサーモンの遺伝子に、マスノスケから成長ホルモンの遺伝子を、また、オーシャンパウト（英語版）から転写開始の遺伝子領域プロモーターを組込んだ結果、天然のアトランティックサーモンの約半分の期間で、より大型に成長する特徴をもつ。

申請から約20年後の2015年11月19日、アメリカ食品医薬品局（FDA）は、これを食品認可した^[7]。これはFDA初の遺伝子組み換え動物の承認となった。

カナダでも2016年5月に政府がアクアドバンテージ・サーモンを食品認可し、翌2017年、カナダでの食用販売が始まった^[8]。カナダでは遺伝子組み替えの表示義務がない。環境団体は販売に反対している^[9]。

脚注[編集]

関連項目[編集]

• サケ類
• 魚の一覧

外部リンク[編集]

• マスノスケの淡水及び海水飼育 - 近畿大学水産研究所報告 Bulletin of the Fisheries Laboratory of Kinki University 2 pp.129-142 19841030
• マスノスケ (PDF) - 札幌市豊平川さけ科学館

왕연어는 연어목 연어과의 물고기이다.

특징

왕연어의 머리 뒷부분과 윗부분은 청록색, 빨간색 또는 보라색이고, 옆면과 복부 표면은 은색이다. 그것은 꼬리에 검은색 반점과 상반신이 있다. 성체의 몸길이는 24cm에서 100cm까지 다양하지만, 최대 180cm까지 자랄 수 있다. 평균 몸무게는 4.5~22.7kg이지만, 최대 75kg에 이를 수 있다.

참조

• “왕연어”. Intergrated Taxonomic Infomation System. 2006년 1월 30일에 확인함.^{[깨진 링크(과거 내용 찾기)]}