Coho Salmon (Oncorhynchus kisutch), or silver salmon, are located in the coastal waters of Alaska. The Coho commonly range southeast to Point Hope on the Chukchi Sea and in the Yukon River to the Alaska-Yukon border. Silver salmon are highly adaptable and can make their home in nearly all accessible bodies of fresh water. These homes can be anything from large transboundary watersheds to small tributaries, such as streams. An adult Coho can weigh eight to twelve pounds and be two to two and a half feet long. Coho weighing as much as thirty one pounds have been recorded. Adult Coho found in salt water or newly arrived in fresh water are bright silver with small black spots on the back and on the upper lobe of the caudal fin. One can distinguish a Coho from a Chinook by the Chinook's lack of the black spotting, and the Chinooks black gums; a Coho's gums are grayish. Both Coho sexes (when spawning) have dark backs and heads with sides that range in color from red to maroon. Male Coho develop a "kype"; a prominent hooked snout with large teeth. Young Coho salmon have eight to twelve "parr" marks evenly distributed above and below their lateral line. The parr marks are narrower than the interspaces. The adipose fin is generally of one color. The a long white-tipped edge lies along the anal fin, with the other fins carrying an orange tint.
From July to November Coho salmon enter spawning streams during periods of high runoff. Coho runs are timed with the particular needs of each stock. Some adults who need to travel streams with barrier falls arrive in July when the water is low and the falls are passable. Coho adults arrive early at big streams and rivers, as they need several weeks or months to reach headwater spawning grounds. Water temperature is also a mitigating factor in Coho spawning runs: low temperatures cause eggs to mature slowly, so spawners have evolved early run timing to compensate. Conversely, warm temperatures produce late spawners. Adults hold in pools until eggs ripen, then move onto spawning grounds. Most Coho spawn at night. The female will dig a nest, called a "redd", and deposit twenty four hundred to forty five hundred eggs. The male will then arrive to fertilize the eggs. These eggs develop during the winter months, hatch in early spring. The Coho embryos remain in the gravel taking nourishment from the egg yolk until they emerge in May or June. The emergent "fry" occupy shallow stream margins. As they grow, Coho salmon establish territories, which they defend from other salmonids. Coho are fond of ponds, lakes, and pools in streams and rivers. These areas are usually feature submerged woody debris, quiet areas free of current, where they feed upon drifting insects.
To avoid the winter floods, juvenile Coho will migrate many miles during the fall to find an off-channel habitat. Some Coho leave fresh water in the spring and rear in brackish estuarine ponds and then migrate back into fresh water in the fall. Coho salmon may spend one to three winters in streams and may spend up to five winters in lakes before migrating to the sea as "smolt". The time Coho spend at sea varies. Some males (called "jacks") mature and return after only six months at sea, reaching a length of about twelve inches. Most Coho stay eighteen months before returning as full size adults.
The Coho salmon is a desirable sport fish and is sought after in fresh and salt water from July to September. Over two hundred thousand Coho were taken in Alaska in the year 1986 alone. Coho are fished in saltwater by trolling with herring or flies from the shore. In fresh water a Coho will go after salmon eggs, flies, spoons, or spinners. Coho are fighters, and will put up a terrific fight for anglers using only light tackle.
- Interior Alaska: Fairbanks, Fort Yukon, Denali National Park
- Southcentral: Anchorage, Seward, Kenai Fjords and Peninsula
- Southeast: Juneau, Ketchikan, Misty Fjords Monument and Tongass National Forest
- Western: Kodiak, Wales, Lake Clark, Katmai National Park
- Northern: Prudhoe Bay, Barrow, Gates of the Arctic National Park, Kobuk Valley
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