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.
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.
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.
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.