AKA: silver salmon, silversides, hookbill, hooknose, sea trout, blueback; French: saumon coho; Japanese: gin-zake
Average lifespan in the wild: 2 to 4 years
Size: Up to 38.5 in (98.7 cm)
Average Weight: 5 to 12 lbs (2.3 to 5.4 kg), Record 33 lbs
Did you know? The coho salmon was introduced from Pacific waters into the Great Lakes and is now abundant there.
The scientific name for Coho is Oncorhynchus kisutch.
Coho fry live in rivers and streams for over a year. They prefer smaller streams than Chinook and smaller gravel. Coho feed on Zooplankton, insects and small fish while in the river. Oxygen levels and cover are important for survival. Logging close to steams contributes to high mortality, however, now most logging close to streams is controlled. Coho can be found from Russia to Siberia and California up to Alaska.
The coho, a member of the Salmonidae family, can be found in most of the same environments as the chinook salmon. It’s known for its ability to fight in spectacular fashion, acrobatically leaping out of the water. And, like the chinook, it’s a very important sport and commercial fish, especially on the Northwest Coast of North America. It has been important both as food and in American Indian culture.
Coho are anadromous, and can adapt to live entirely in fresh water. They have been successfully transplanted to the Great Lakes of North America. Due to a variety of man-caused environmental changes and overfishing, its populations have declined. Some runs are even on the endangered or threatened list.
Despite their smaller size, they make for a very popular sportfish in all their range. Coho are found on the Pacific coast everywhere chinook are, and in the Great Lakes where their population comes almost entirely from hatcheries. It is caught using a variety of angling: boat fishing, from the bank or wading in rivers.
Anglers find that the coho is more fun to catch on lighter tackle than chinook, although similar methods are used for both. Unlike the chinook that takes the fight to the deep waters, it stays mostly on the surface and takes the battle to the air. But don’t let this fool you, the coho still has a great deal of stamina to fight. Coho meat is red and sold fresh, frozen, canned or smoked.
Coho have a longer body with a conical head. For the better part of its life, its color stays a dark blue or blue/green on the top with silver sides and belly. They also have black spots on their back and on the upper lobe of the caudal fin. Unlike chinook, coho don’t have black spots on the lower lobe of the tail and their gums are white or grey as opposed to black.
Upon returning to fresh water to spawn, coho will have dark backs and heads, and maroon or red sides. Males develop a double hooked nose (kype) with large teeth. This prevents the male from closing its mouth.
Young coho have 8 to 12 parr marks below and above the lateral line. The adipose fin solidly colored, the anal fin has a long leading edge, usually with a white tip. And all fins usually have an orange tint.
Most coho are caught between 4 and 8 lbs. The sport record was caught out of the Great Lakes and weighed in at 33 pounds 4 ounces. Some have been caught in Alaska that reached 31 pounds, but the average is 8 to 12 pounds and 24 to 30 inches long. Due to the fact that coho are strong fighters anyhow, when they reach sizes above 15 pounds, they become a big challenge to fishermen.
Coho are native to most of the Pacific rim. On the Asian side, they range from northern Japan to the former USSR. In North America, they range from southern California to the tip of Alaska. The highest population is found on the coast of British Columbia, Canada and Alaska. They have also been found as far south as Baja California, Mexico.
Coho have been introduced into the Great Lakes and freshwater lakes in Alaska and the west coast of the U.S. They’ve also been introduced to Maine, Maryland, and Louisiana in the U.S. as well as Alberta, Canada; Argentina and Chile. Coho do not typically spawn successfully in the transplanted areas, with an exception of the Great Lakes around Michigan. Great Lakes coho are maintained through stocking.
Life cycle and typical behaviors:
As with all Pacific salmon, coho are anadromous. They are hatched in rivers; spend most of their life in the ocean and return to spawn in their rivers of origin. Freshwater coho that have been transplanted hatch in tributaries migrate out to lakes and return to the rivers to spawn. All coho die after spawning.
Male adult sea-run coho return to their streams when they reach 2 or 3 while females return to spawn when they are 3. All coho spend their first year of life in the stream where they are hatched.
Eggs laid vary between 1500 and 4500, depending on the size of the female and the run.
Runs back to the rivers vary in timing. In Alaska, coho return between July and November. In California, most runs occur between September and March, and spawning occurs November to January. Great Lakes coho return to streams from August to October. Running times reflect specific factors, such as barrier falls that can only be passed at certain times of the year. It is also regulated by the temperature at spawning grounds: low temperature eggs develop slowly and cause an early run time, while warmer waters cause a late run.
Coho will not feed during their spawning migration, so they gradually get weaker. During the run, they use their body weight for energy and to produce reproductive cells. Adults hold in pools while they “ripen”, then move to spawning areas. Females deposit eggs in nests made of gravel (also known as redds), which they dig. Eggs will usually hatch in early spring. Embryos remain and develop in the gravel, consuming their egg sac. Fry emerge to live in shallow stream margins and once old enough, defend their territory. They live in ponds, lakes, pools in rivers and streams in a quiet and calm area. There they hunt insects.
In fall, young coho travel to locate an off-channel habitat to pass the winter. Some coho leave the river and migrate to ponds then back to freshwater. They spend between one and 3 winters in these streams, and up to 5 in lakes before heading to the sea in their smolt stage. Coho vary in the amount of time they spend at sea. Jacks are males who have matured and return after 6 months. At this stage, they are usually 12 inches long. But most coho stay 18 months before their return to the stream.
Scientists are still unsure about the coho’s range. It is thought that there are more on the Pacific coast of North America than anywhere else. Maturing coho migrate northward in the spring and can be found in the central gulf of Alaska in mid-summer. Later, they move to shore and follow it until they get to their home stream. Coho have been known to travel up to 1,200 miles, although this is rare.
Great Lake coho migrate several miles from their natal river, in search of food and due to changes in temperature. Warmer temperatures drive the fish to the deeper cooler areas of lakes, and feeding fish are also located there.
Young coho in freshwater feed on plankton and insects. When they reach the ocean, their diet consists of herring, pilchards, sand lance, squid and crustaceans. Coho that live only in freshwater also eat plankton and insects in their youth and baitfish once they reach maturity (usually alewives and smelt). Coho were actually introduced to keep populations of baitfish.