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What is a Coho Salmon?

J.M. Densing
J.M. Densing

The Coho salmon is a medium sized, silvery colored fish belonging to the salmon family that is found mainly in the northern Pacific Ocean and in coastal streams and rivers. The scientific name for this fish is Oncorhynchus kisutch, and it is also known as the silver salmon. The Coho salmon spends part of the life span in freshwater, and part in saltwater, migrating back to the place of birth to reproduce or spawn. The fish is a common target of both commercial and sport fishermen.

The adult Coho salmon usually grows to a length of 24 to 30 inches (about 61 to 76 cm) and a weight of about eight to 12 pounds (about 3.6 to 5.4 kg). They have silvery colored sides with greenish or blue backs. Many also have black spots on their backs while they are in salt water, and young fish often have an orange tint on the fins. As they mature and become ready to spawn they develop hooked snouts, especially the males.

Coho salmon migrate back to their birthplace in order to spawn.
Coho salmon migrate back to their birthplace in order to spawn.

The natural habitat of the Coho salmon is the northern Pacific area, both in the ocean and in streams and rivers located near the coast. Its range spreads from central California to Alaska, through the Aleutian Islands, to Siberia and south to the northern parts of Japan. The Coho salmon begins life in slow moving freshwater streams and rivers, remaining there for at least a year. The fish then migrates to saltwater coastal ocean environments for a period of about one to two years, returning to the area of their birth to spawn at about three years of age.

Coho salmon is found in the northern Pacific ocean, including near the western U.S., Siberia and Japan.
Coho salmon is found in the northern Pacific ocean, including near the western U.S., Siberia and Japan.

The diet of the Coho salmon consists of plankton and aquatic insects during the freshwater stages of life. They will often spend time hiding in the cover of plants and submerged debris, darting out quickly to feed from time to time. While in the saltwater ocean stage, they usually remain in shallower coastal water with plenty of available cover and feed primarily on small fish. During all stages they are at risk from commercial and sport fishing, and they are an important food source and industry in some areas.

Coho salmon typically spend their first year of life in rivers or streams.
Coho salmon typically spend their first year of life in rivers or streams.

At spawning time, the adult Coho salmon return to the area where they were born to spawn; the time of year that they return depends on the place and ease of passage, but it is often spring or summer. The female salmon digs the nest, also called a redd, and lays up to 4500 eggs which are then fertilized by the male. The Coho Salmon only spawns once during its lifetime, dying soon after. The baby fish, called fry, hatch in early spring, but remain in the nest developing further until they emerge in May or June. They spend the winter in the freshwater environment before setting out for the sea in the following spring, and continuing the life cycle.

Frequently Asked Questions

What is a Coho Salmon?

Due to the mercury levels of salmon, pregnant women are typically advised to limit consumption of the fish.
Due to the mercury levels of salmon, pregnant women are typically advised to limit consumption of the fish.

Coho salmon, also known as silver salmon, are anadromous fish native to the Pacific Northwest. They are born in freshwater streams, migrate to the ocean to mature, and return to their birthplace to spawn. Coho are recognized for their silver sides and dark blue backs, with males developing a distinctive hooked nose during spawning season.

How can you identify a Coho Salmon?

Identifying a Coho salmon is straightforward: look for bright silver sides and a dark blue back. During spawning, males develop a pronounced kype, or hooked nose, and their coloration shifts to a deeper red. Both sexes have small black spots on their back and upper lobe of the tail fin, distinguishing them from other salmon species.

What is the typical lifespan of a Coho Salmon?

Coho salmon typically live for about three years. They spend the first half of their life in freshwater environments before migrating to the ocean, where they grow rapidly. After maturing in the ocean, they return to their natal freshwater habitats to spawn and then die shortly after, completing their life cycle.

Where do Coho Salmon live?

Coho salmon are found across the North Pacific, from Alaska to California in North America, and from Russia to Japan in Asia. They inhabit coastal waters and spawn in freshwater streams and rivers. Their habitat choice is influenced by water temperature, stream flow, and the availability of suitable spawning grounds.

What do Coho Salmon eat?

Coho salmon have a diverse diet that changes as they grow. Juveniles feed on insects, zooplankton, and small fish in freshwater. As adults in the ocean, their diet expands to include larger fish, squid, and crustaceans. This rich diet helps them accumulate the energy needed for their spawning migration and reproduction.

Why are Coho Salmon important to the ecosystem?

Coho salmon play a crucial role in their ecosystems. They are a keystone species, meaning their presence affects the structure of the ecological community. As predators, they help maintain balanced fish populations, and as prey, they provide food for larger species. Their carcasses also bring essential nutrients from the ocean to freshwater ecosystems, supporting a wide range of organisms.

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    • Coho salmon migrate back to their birthplace in order to spawn.
      By: max5128
      Coho salmon migrate back to their birthplace in order to spawn.
    • Coho salmon is found in the northern Pacific ocean, including near the western U.S., Siberia and Japan.
      By: pilipphoto
      Coho salmon is found in the northern Pacific ocean, including near the western U.S., Siberia and Japan.
    • Coho salmon typically spend their first year of life in rivers or streams.
      By: Fyle
      Coho salmon typically spend their first year of life in rivers or streams.
    • Due to the mercury levels of salmon, pregnant women are typically advised to limit consumption of the fish.
      By: Halfpoint
      Due to the mercury levels of salmon, pregnant women are typically advised to limit consumption of the fish.