Coho SalmonOncorhynchus kisutchWhere and when to see them

Coho salmon, also called silver salmon, are Pacific salmon native to the North Pacific and its coastal rivers. In the Columbia River basin, they migrate between freshwater tributaries and the Pacific Ocean. Their life cycle connects marine and river ecosystems, carrying ocean-derived nutrients inland when adults return to spawn. Coho support fisheries and have longstanding cultural importance to Indigenous peoples. Despite their global conservation status, some Columbia River populations face serious pressures from habitat loss, barriers to migration, warming water, and other environmental changes.

Size

Adults typically measure 60-90 cm (24-35 in) long.

Weight

Adults commonly weigh 3-6 kg (7-13 lb).

Lifespan

Usually 3 years, although some mature earlier or later.

Status

Least Concern globally; some Columbia River populations are federally listed as threatened.

Most coho are anadromous, hatching in freshwater, growing at sea, and returning to freshwater to reproduce. Juveniles usually spend about a year in streams before migrating downstream as smolts in spring. At sea, they feed actively and may travel substantial distances along the coast. Returning adults generally home to their natal watershed, using chemical cues during the freshwater portion of their migration. Females excavate gravel nests called redds with movements of their tails. Males compete for access to females, and fertilization occurs externally as eggs and milt are released. Adults die after spawning, while their offspring develop within the gravel before emerging.

• Silver salmon is another common name for coho.
• Some males return early as smaller, sexually mature fish called jacks.
• A female may distribute her eggs among several pockets within a redd.
• After spawning, adult carcasses provide nutrients for stream food webs and nearby wildlife.

Wildlife opportunities depend on the river reach, water levels and species. River-specific viewing months have not been confirmed; general species seasons are not a local sighting forecast.

Coho use cool freshwater streams and rivers for spawning and early development, estuaries during migration, and the North Pacific for marine growth. In the Columbia basin, the main river serves chiefly as a migration corridor linking the ocean with tributary habitats. Juveniles favor pools, side channels, and sheltered stream margins, especially where wood and overhanging vegetation provide cover. Connected floodplain habitats can offer important refuge during high flows. Successful spawning requires suitable gravel and flowing, oxygenated water, while warm temperatures and excessive fine sediment can reduce habitat quality.

Young coho eat aquatic insect larvae, insects that fall onto the water, and small crustaceans. Larger juveniles may also consume small fish. At sea, coho feed on schooling fishes such as herring and anchovies, along with squid and crustaceans. Adults generally stop feeding once they enter freshwater on their spawning migration.

Common name

Coho Salmon

Scientific name

Oncorhynchus kisutch

Animal group

Fish

Size

Adults typically measure 60-90 cm (24-35 in) long.

Weight

Adults commonly weigh 3-6 kg (7-13 lb).

Lifespan

Usually 3 years, although some mature earlier or later.

Status

Least Concern globally; some Columbia River populations are federally listed as threatened.

Identification

Ocean-phase and newly returning coho have bright silver sides, a dark blue-green back, and small black spots on the back and upper lobe of the tail. The lower tail lobe usually lacks the prominent spotting typical of Chinook salmon. Coho have a dark mouth interior but a pale gum line along the lower jaw, unlike the dark lower gum line of Chinook. Spawning adults become darker, often developing reddish sides, while males develop a strongly hooked snout and enlarged teeth.