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).
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. Mature females may be darker than males, with both showing a pronounced hook on the nose.
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.
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.Coho salmon have also been introduced in all the Great Lakes, as well as many landlocked reservoirs throughout the United States. 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.
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.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. The total North Pacific yields of the pink salmon, chum salmon and sockeye salmon are some 10–20 fold larger by weight.
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.
It is also pursued by fly fishermen in salt water.
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.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. 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.
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.Four of these ESUs are listed under the U.S. Endangered Species Act (ESA). 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.
The Puget Sound/Strait of Georgia ESU in Washington is an NMFS "Species of Concern".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. [ citation needed ]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.
Salmon is the common name for several commercially important species of euryhaline ray-finned fish from the family Salmonidae, which are native to tributaries of the North Atlantic and North Pacific basin. Other closely related fish in the same family include trout, char, grayling, whitefish, lenok and taimen.
The Napa River is a river approximately 55 miles (89 km) long in the U.S. state of California. It drains a famous wine-growing region called the Napa Valley, in the mountains north of the San Francisco Bay. Milliken Creek and Mt. Veeder watersheds are a few of its many tributaries. The river mouth is at Vallejo, where the intertidal zone of fresh and salt waters flow into the Carquinez Strait and the San Pablo Bay.
A salmon run is an annual fish migration event where many salmonid species, which are typically hatched in fresh water and live most of the adult life downstream in the ocean, swim back against the stream to the upper reaches of rivers to spawn on the gravel beds of small creeks. After spawning, all species of Pacific salmon and most Atlantic salmon die, and the salmon life cycle starts over again with the new generation of hatchlings.
Steelhead, or occasionally steelhead trout, is the common name of the anadromous form of the coastal rainbow trout (Oncorhynchus mykiss irideus) or Columbia River redband trout. Steelhead are native to cold-water tributaries of the Pacific basin in Northeast Asia and North America. Like other sea-run (anadromous) trout and salmon, steelhead spawn in freshwater, smolts migrate to the ocean to forage for several years and adults return to their natal streams to spawn. Steelhead are iteroparous, although survival is approximately 10–20%.
The eulachon, also called the candlefish, is a small anadromous species of smelt that spawns in some of the major river systems along the Pacific coast of North America from northern California to Alaska.
The chum salmon, also known as dog salmon or keta salmon, is a species of anadromous salmonid fish from the genus Oncorhynchus native to the coastal rivers of the North Pacific and the Beringian Arctic, and is often marketed under the trade name silverbrite salmon in North America. The English name "chum salmon" comes from the Chinook Jargon term tzum, meaning "spotted" or "marked"; while keta in the scientific name comes from Russian, which in turn comes from the Evenki language of Eastern Siberia. The term 'Dog Salmon' is most commonly used in Alaska and refers to the Salmon who's flesh Alaskans use to feed their dogs.
The Chinook salmon is the largest and most valuable species of Pacific salmon in North America, as well as the largest in the genus Oncorhynchus. 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).
The sockeye salmon, also called red salmon, kokanee salmon, blueback salmon, or simply sockeye, is an anadromous species of salmon found in the Northern Pacific Ocean and rivers discharging into it. This species is a Pacific salmon that is primarily red in hue during spawning. They can grow up to 84 cm in length and weigh 2.3 to 7 kg (5–15 lb). Juveniles remain in freshwater until they are ready to migrate to the ocean, over distances of up to 1,600 km (1,000 mi). Their diet consists primarily of zooplankton. Sockeye salmon are semelparous, dying after they spawn. Some populations, referred to as kokanee, do not migrate to the ocean and live their entire lives in fresh water.
Pink salmon or humpback salmon is a species of anadromous fish in the salmon family. It is the smallest and most abundant of the Pacific salmon. The scientific species name is based on the Russian common name for this species gorbúša (горбуша), which literally means humpie.
Oncorhynchus is a genus of fish in the family Salmonidae; it contains the Pacific salmon and Pacific trout. The name of the genus is derived from the Greek ὄγκος + ῥύγχος, in reference to the hooked snout that the males develop during mating season.
Lagunitas Creek is a 24 miles (39 km)-long northward-flowing stream in Marin County, California. It is critically important to the largest spawning runs of endangered coho salmon in the Central California Coast Coho salmon Evolutionary Significant Unit.
The Mattole River is a river on the north coast of California, that flows northerly, then westerly into the Pacific Ocean. The vast majority of its 62 miles (100 km) course is through southern Humboldt County, though a short section of the river flows through northern Mendocino County. Communities, from north to south, closely associated with the Mattole River include: Petrolia, Honeydew, Ettersburg, Thorn Junction, and Whitethorn. The river enters the ocean at the Mattole Estuary about 4 miles (6.4 km) west-southwest of Petrolia and 10 miles (16 km) south of Cape Mendocino.
The Baker River is an approximately 30-mile (48 km), southward-flowing tributary of the Skagit River in northwestern Washington in the United States. It drains an area of the high North Cascades in the watershed of Puget Sound north of Seattle, and east of Mount Baker. With a watershed of approximately 270 square miles (700 km2) in a complex of deep valleys partially inside North Cascades National Park, it is the last major tributary of the Skagit before the larger river reaches its mouth on Skagit Bay. The river flows through Concrete, Washington, near its mouth and has two hydroelectric dams owned by Puget Sound Energy.
San Gregorio Creek is a river in San Mateo County, California. Its tributaries originate on the western ridges of the Santa Cruz Mountains whence it courses southwest through steep forested canyons. The San Gregorio Creek mainstem begins at the confluence of Alpine and La Honda Creeks, whence it flows 12 miles (19 km) through rolling grasslands and pasturelands until it meets the Pacific Ocean at San Gregorio State Beach. It traverses the small unincorporated communities of La Honda, San Gregorio, Redwood Terrace and Sky Londa.
Boise Creek is a stream in Humboldt County, California, United States. From its origin on Orleans Mountain it flows 8.5 miles to join the Klamath River about 2.25 miles southeast of Orleans, California. The creek lies within the Six Rivers National Forest and is part of the Lower Klamath River Watershed.
Salmon population levels are of concern in the Atlantic and in some parts of the Pacific. Salmon are typically anadromous - they rear and grow in freshwater, migrate to the ocean to reach sexual maturity, and then return to freshwater to spawn. Determining how environmental stressors and climate change will affect these fisheries is challenging due to their lives split between fresh and saltwater. Environmental variables like warming temperatures and habitat loss are detrimental to salmon abundance and survival. Other human influenced effects on salmon like overfishing and gillnets, sea lice from farm raised salmon, and competition from hatchery released salmon have negative effects as well.
Fish go through various life stages between fertilization and adulthood. The life of a fish start as spawned eggs which hatch into immotile larvae. These larval hatchlings are not yet capable of feeding themselves and carry a yolk sac which provides stored nutrition. Before the yolk sac completely disappears, the young fish must mature enough to be able to forage independently. When they have developed to the point where they are capable of feeding by themselves, the fish are called fry. When, in addition, they have developed scales and working fins, the transition to a juvenile fish is complete and it is called a fingerling, so called as they are typically about the size of human fingers. The juvenile stage lasts until the fish is fully grown, sexually mature and interacting with other adult fish.
The prickly sculpin is a species of ray-finned fish belonging to the family Cottidae, the typical sculpins. It is native to the river drainages of the Pacific Slope of North America from Seward, Alaska south to the Ventura River of Southern California. It extends east of the Continental Divide in the Peace River of British Columbia. It has also been introduced to several reservoirs in Southern California.
Pre-spawn mortality is a phenomenon where adult coho salmon, Oncorhynchus kisutch, die before spawning when returning to freshwater streams to spawn. It is also known as Urban Runoff Mortality Syndrome in more recent studies. This occurrence has been observed in much of the Puget Sound region of the Pacific Northwest. During fall migration, salmonids pass through urban watersheds which are contaminated with stormwater runoff. As the coho salmon pass through these waters, many will show symptoms of lethargy, loss of equilibrium and disorientation, and die within a few hours of showing these symptoms. These symptoms and behaviors are prevalent after rain events. Mortality often occurs before salmon have the opportunity to spawn, which is determined by cutting open female carcasses and observing for unfertilized eggs. Rates of pre-spawn mortality could impact the local salmon populations. Based on model projections, if rates continue, populations of coho salmon could become extinct within the next few decades.
The National Oceanic and Atmospheric Administration, in cooperation with the U.S. Fish and Wildlife Service and Environmental Protection Agency, groups steelhead and salmon into distinct population segments (DPS). There are currently 15 DPS for steelhead and 31 evolutionarily significant units (ESU) for five species of Pacific salmon Oncorhynchus. The boundaries of these areas are used to determine whether specific populations of a species should be designated threatened or endangered species under the Endangered Species Act.