The scientific name Oncorhynchus kisutch was derived from the Greek roots onkos, (hook), rynchos (nose), and kisutch, the ordinary name in Siberia and Alaska. Some other common names for Oncorhynchus kisutch are coho, silver, blueback, and hook nose salmon. (StreamNet, 1996)
Perception Channels: tactile ; chemical
There has been a serious decline of wild coho stocks in the Strait of Georgia, due to loss of habitat (from dams) and overfishing. A plan of harvest management has been developed and implemented by the Dept. of Fisheries and Oceans. (Pacific Salmon Foundation, 1995)
US Federal List: no special status
CITES: no special status
State of Michigan List: no special status
Oncorhynchus kisutch make a good meal. Often, coho are either sold frozen or canned by commercial fisherman. Twice as many coho salmon are harvested commercially in North America than in Asia. During the late 1950's about 10 million coho salmon per year were caught. These numbers declined to 4.5 million coho per year in the 60's and have now risen to about 10.5 million coho per year. Fishing for coho is also an important sport for trollers and flyfisherman. (McNeil et. al, 1980)
In fresh water streams and rivers, juvenile coho salmon defend territories and compete for limited feeding sites with other fish. In order to attain these feeding sites, they may charge or chase other fish away, as growth and fitness depend on it. Coho salmon attack prey by sprinting and striking. They are able to maneuver well in order to capture prey. In fresh water, coho eat insects and smaller fish. When they move to the ocean they begin to grow rapidly due to the abundance of food. Once these fish reach the ocean their diet changes to other fish, such as herring and squid (Groot et. al., 1995).
Oncorhynchus kisutch, commonly known as coho salmon, are primarily found in coastal waters. Coho salmon do not range widely in the open ocean like that of many other salmon species. Oncorhynchus kisutch are also found in fresh water, during their first year and later while spawning. They are found in fresh streams of the North Pacific, ranging from Baja, California to Alaska (Wheeley, 1985).
Biogeographic Regions: nearctic (Native ); arctic ocean (Native ); atlantic ocean (Native ); pacific ocean (Native )
Coho Salmon live in fresh and ocean water. In fresh water, coho like relatively slow moving water with fine gravel. In the ocean, coho tend to live closer to shores than in the open ocean. (StreamNet, 1996)
Aquatic Biomes: rivers and streams; coastal
Average lifespan
Status: wild: 4.1 years.
Average lifespan
Status: wild: 5.0 years.
Average lifespan
Status: wild: 4.0 years.
Oncorhynchus kisutch typically spend the first year of their life in fresh water. Upon moving to the ocean, growth increases dramatically. At about the third year, coho salmon reach maturity. They weigh from 6 to 12 pounds and can be up to 38 inches in length.
Oncorhynchus kisutch are deep-bodied salmon with unique color characteristics. The dorsal surface is a metallic blue while the sides are a silver color. Black spots appear on the back and upper lobe of the caudal fin. A lateral line is also present. The line is curved toward the front of the fish and straightens out as it approaches the back of the fish. While spawning, the fish's back and belly turn dark. Spawning males' sides develop a bright red line and their jaws become hooked (Clemens and Wilby, 1961).
Range mass: 3 to 6 kg.
Other Physical Features: ectothermic ; heterothermic ; bilateral symmetry
Sexual Dimorphism: sexes colored or patterned differently
At three to four years of age, coho salmon reach sexual maturity. From September to October, coho swim to the fresh water streams where they were born (up to 400 miles). Once the fish reach their natal site females dig a nest in a gravel-type area. After the nest is made a female and one male (occasionally 2) breed. In this breeding, the female lays her eggs and the male's sperm is spread over them, thus fertilizing them. After fertilization has occurred, the eggs are buried by other female coho that are digging their nests. Following reproduction, males and females die, giving the waters more nutrients. Larvae hatch 6-8 weeks after fertilization. The larvae remain in the gravel for 2-3 weeks. Coho live in streams or rivers for about a year until they move to the ocean. (Wheeler, 1985)
Average age at sexual or reproductive maturity (male)
Sex: male: 1095 days.
Average age at sexual or reproductive maturity (female)
Sex: female: 1095 days.
The Coho or Silver Salmon (Oncorhynchus kisutch) has black spots on the back and upper lobe of the caudal fin. The gums are light at the base of the teeth. At sea, these salmon are metallic blue above and silver below. Breeding males have dusky green on the back and head, with bright red sides and a black belly; females have bonze to pink-red sides. Spawning males develop a strongly hooked snout and large teeth. Maximum length is around 100 cm. Chinook Salmon (O. tshawytscha) are very similar in appearance to Coho Salmon while at sea, but Chinook Salmon are larger, have black spots on both the upper and lower caudal fin lobes, and have gums that are dark at the base of the teeth. (Page and Burr 1991)
Coho Salmon occur in northeastern Asia and, in North America, in Arctic and Pacific drainages from Point Hope, Alaska, to Monterey Bay, California (occasionally as far south as Baja California). These fish are anadromous, returning from the ocean to the coastal streams or rivers where they were born to spawn. They reproduce just once, then die. (Page and Burr 1991)
For detailed information on the biology and status of this species, including conservation issues, see this resource from the NOAA Fisheries Office of Protected Resources.
The coho salmon (Oncorhynchus kisutch; Karuk: achvuun[1]) is a species of anadromous fish in the salmon family and one of the five Pacific salmon species. Coho salmon are also known as silver salmon or "silvers". The scientific species name is based on the Russian common name kizhuch (кижуч).
.jpg)
During their ocean phase, coho salmon have silver sides and dark-blue backs. During their spawning phase, their jaws and teeth become hooked. After entering fresh water, they develop bright-red sides, bluish-green heads and backs, dark bellies and dark spots on their backs. Sexually maturing fish develop a light-pink or rose shading along the belly, and the males may show a slight arching of the back. Mature adults have a pronounced red skin color with darker backs and average 28 inches (71 cm) and 7 to 11 pounds (3.2 to 5.0 kg), occasionally reaching up to 36 pounds (16 kg). They also develop a large kype (hooked beak) during spawning.[2] Mature females may be darker than males, with both showing a pronounced hook on the nose.[3]
The eggs hatch in the late winter or early spring after six to seven weeks in the redd. Once hatched, they remain mostly immobile in the redd during the alevin life stage, which lasts for 6–7 weeks. Alevin no longer have the protective egg shell, or chorion, and rely on their yolk sacs for nourishment during growth. The alevin life stage is very sensitive to aquatic and sedimental contaminants. When the yolk sac is completely resorbed, the alevin leaves the redd. Young coho spend one to two years in their freshwater natal streams, often spending the first winter in off-channel sloughs, before transforming to the smolt stage. Smolts are generally 100–150 mm (3.9–5.9 in) and as their parr marks fade and the adult's characteristic silver scales start to dominate. Smolts migrate to the ocean from late March through July. Some fish leave fresh water in the spring, spend summer in brackish estuarine ponds, and then return to fresh water in the fall. Coho salmon live in salt water for one to three years before returning to spawn. Some precocious males, known as "jacks", return as two-year-old spawners. Spawning males develop kypes, which are strongly hooked snouts and large teeth.
_1.JPG)
Fingerling
Male ocean phase coho
Male freshwater phase coho
Breeding male
The traditional range of the coho salmon runs along both sides of the North Pacific Ocean, from Hokkaidō, Japan and eastern Russia, around the Bering Sea to mainland Alaska, and south to Monterey Bay, California.[4] Coho salmon have also been introduced in all the Great Lakes, as well as many landlocked reservoirs throughout the United States.[5] A number of specimens, (more than 20), were caught in waters surrounding Denmark and Norway in 2017. Their source is currently unknown, but the salmon species is farmed at several locations in Europe, making it probable that the animal has slipped the net at such a farm.[6]
The total North Pacific harvest of coho salmon in 2010 exceeded 6.3 million fish, of which 4.5 million were taken in the United States and 1.7 million in Russia. This corresponds to some 21,000 tonnes in all.[7] Coho salmon are the backbone of the Alaskan troll fishery; however, the majority are caught by the net fishery (gillnet and seine). Coho salmon average 3.5% by fish and 5.9% by weight of the annual Alaska salmon harvest.[8] The total North Pacific yields of the pink salmon, chum salmon and sockeye salmon are some 10–20 fold larger by weight.[7]
In North America, coho salmon is a game fish in fresh and salt water from July to December, especially with light fishing tackle. It is one of the most popular sport fish in the Pacific Northwest of the United States and Canada. Its popularity is due in part to the reckless abandon which it frequently displays chasing bait and lure while in salt water, and the large number of coastal streams it ascends during its spawning runs. Its habit of schooling in relatively shallow water, and often near beaches, makes it accessible to anglers on the banks, as well as in boats.[9]
It is also pursued by fly fisherman in salt water.[10]
Ocean-caught coho is regarded as excellent table fare. It has a moderate to high amount of fat, which is considered to be essential when judging taste. Only spring chinook and sockeye salmon have higher levels of fat in their meat. When smoking coho it is best to use a cold-smoking rather than hot-smoking process, due to their lower fat content compared to sockeye and chinook.
Historically coho, along with other species, has been a staple in the diet of several indigenous peoples, who would also use it to trade with other tribes farther inland. The coho salmon is also a symbol of several tribes, representing life and sustenance.
In their freshwater stages, coho feed on plankton and aquatic invertebrates in the benthos and water column, such as Chironomids, midge larvae, and terrestrial insects that fall into the water.[11] Upon entering the marine environment, they switch to a diet of plankton and fish, with fish making up most of their diets after a certain size.[12] Adult coho feed on a vast variety of prey items that depend on the region they reside in during their second year at sea. Spawning habitats are small streams with stable gravel substrates.
Salmonid species on the west coast of the United States have experienced dramatic declines in abundance during the past several decades as a result of human-induced and natural factors.[13]
The U.S. National Marine Fisheries Service (NMFS) has identified seven populations, called Evolutionary Significant Units (ESUs), of coho salmon in Washington, Oregon and California.[14][15] Four of these ESUs are listed under the U.S. Endangered Species Act (ESA).[16] These are the Lower Columbia River (threatened), Oregon Coast (threatened), Southern Oregon and Northern California Coasts (threatened), and Central California Coast (endangered). The long-term trend for the listed populations is still downward, though there was one recent good year with an increasing trend in 2001.[17]
The Puget Sound/Strait of Georgia ESU in Washington is an NMFS "Species of Concern".[18] Species of Concern are those species for which insufficient information prevents resolving the U.S. National Oceanic and Atmospheric Administration's concerns regarding status and threats and whether to list the species under the ESA.
On May 6, 1997, NMFS, on behalf of the Secretary of Commerce, listed as threatened the Southern Oregon/Northern California Coast coho salmon ESU.[19] The coho salmon population in the Southern Oregon/Northern California region has declined from an estimated 150,000–400,000 naturally spawning fish in the 1940s to fewer than 10,000 naturally producing adults today. These reductions are due to natural and man-made changes, including short-term atmospheric trends (such as El Niño, which causes extremes in annual rainfall on the northern California coast), predation by the California sea lion and Pacific harbor seal, and commercial timber harvesting.
More than 680,000 coho salmon returned to Oregon in 2009, double that of 2007. The Oregon Department of Fish and Wildlife required volunteers to herd fish into hatchery pens. Some creeks were reported to have so many fish, "you could literally walk across on the backs of coho," claimed a Portland television station. 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 2009 run was so large, food banks were able to freeze 40 tonnes (39 long tons; 44 short tons) for later use.[20]
The coho salmon (Oncorhynchus kisutch; Karuk: achvuun) is a species of anadromous fish in the salmon family and one of the five Pacific salmon species. Coho salmon are also known as silver salmon or "silvers". The scientific species name is based on the Russian common name kizhuch (кижуч).
