Pacific Salmon

Genus Oncorhynchus

“Salmon” is the casual name given to a group of ray-finned fish in the family Salmonidae. Other groups in this family include graylings, chars, trout, and freshwater whitefishes. Of the salmon, those that reside in pacific waters belong to the genus Oncorhynchus. A few of the fish featured at the Mason Wildlife Exhibit are members of this genus.

Chinook Salmon

Quick Facts

Common Name: Chinook Salmon (a.k.a. King Salmon)

Scientific Name: Oncorhynchus tshawytscha

Size: Chinook are the largest of all salmon species, with average adults exceeding 40 pounds; individuals over 120 pounds have been reported.

Habitat: Prefers an algae-rich ocean and a clean oxygenated freshwater river

Life Span: The average Chinook lives 4-6 years but many live up to 8 or 9

Diet: Insects, amphipods, and crustaceans while young and other fish when older

Migration: The Yukon River hosts their longest migration route at 1900 miles with elevation changes of up to 7,000 feet. Others spawn closer to the ocean and use small coastal streams to spawn.

fish, salmon, chinook

The phases of a Chinook’s appearance

Did you know?

  • Chinook salmon are also called King, spring salmon, June hog, and blackmouth
  • Ocean chinook are silver with a greenish blue sheen. As they prepare to spawn, the body darkens with a reddish hue on the fins and belly
  • The teeth of spawning males become enlarged and the snout develops into a hook
  • Because of their large size and presence in coastal waters, they are one of the favored prey of killer whales
  • Chinook salmon can be distinguished from other salmon by their black gums and black spots on their back and tail

Chinook life cycle

Chinook have a complicated life cycle that takes years to complete and can span thousands of miles from headwater streams to the North Pacific Ocean. They are born in freshwater and move among a wide variety of freshwater habitats to find food and cover. Smolts migrate to the sea where they reach adulthood and spend a large portion of their life. After 1-5 winters at sea, they return to spawn and then die.

Chum Salmon

Quick Facts

Common Name: Chum Salmon

Scientific Name: Oncorhynchus keta

Size: Chum salmon average from 8-15 pounds but can weigh up to 45 pounds. Typical length is up to 4 feet.

Maximum longevity: Up to 7 years in the wild. They will die shortly after spawning.

Diet: After hatching in their natal streams juveniles feed on insects and other fresh water invertebrates. Upon migrating to estuarine and marine habitats, they will begin to feed on copepods, mollusks, tunicates, and other fish.

Range: The chum salmon is native on both the North American and Asian continents. It spawns from the Mackenzie River in the Arctic to as far south as Oregon. Stocking attempts to introduce chum outside their range have failed to generate reproducing populations. 

Image by Knepp Timothy, Fish and Wildlife Service


When in the ocean, chum salmon are metallic greenish-blue along the back with black speckles. As they enter freshwater, their appearance changes dramatically. Both sexes develop a tiger stripe pattern of bold red and black stripes. Males develop a striking calico pattern with the front two-thirds of the flank marked by a bold, jagged, reddish line and the back third by a jagged black line. Spawning femailes are less flamboyantly colored.

Eggs and Young

Eggs are deposited in the freshwater streams during December. The embryos develop within the eggs and hatch after approximately 4 months. The young migrate to ocean waters almost immediately after hatching. When they first enter saltwater they assemble in small schools and reside close to shore to avoid predators. As the young fish grow, they gradually move to deeper waters and migrate towards open ocean waters. They remain in the ocean 4-6 years before returning to their hatching grounds to spawn.

Male chums develop large “teeth” during spawning, which resemble canine teeth. This may explain the nickname “dog salmon”.

Chum salmon newborns

Chum salmon eggs

Coho Salmon

Salmon caught on a research cruise. Photo by NOAA on Unsplash.

Quick Facts

Common Name: Coho Salmon

Scientific Name: Oncorhynchus kisutch

Size: They range from about 7 pounds to 11 pounds. Average length is 28 inches. In rare cases, they can reach up to 36 pounds and be 3 to 4 feet long.

Lifespan: Average is 3 to 5 years

Diet: River dwelling Cohos feed on plankton and insects. As they get larger and move out to sea, they switch to eating small fish.

Behavior: Cohos migrate from a marine environment into freshwater streams and rivers of their birth; they spawn only once and then die.

Life Cycle

The Coho salmon prefer gravel streambeds for egg-laying. Coho eggs hatch about 7 weeks after they’re laid in late winter and spend another 7 weeks inside their nests. Once they leave they spend 1-2 years in their natal streams. As soon as they start developing adult characteristics, they head for the deep sea. Of all the types of salmon, Coho spend the least amount of time in the ocean – they only live there for 1-3 years before returning to spawn. This makes them one of the most short-lived breeds of wild salmon.


During their ocean phase, Coho have silver sides and dark blue backs. During spawning phase they develop a pronounced red skin color with darker backs. Mature females may be darker than males with both showing a pronounced hook on the nose.

Coho spawning on the Salmon River. Photo by the Bureau of Land Management.


Cohos are pacific fish and live along both the west coast of North America and the east coast of Asia. Their range extends from Japan and Russia to Alaska and California. They have been introduced to several landlocked locations within the US, including all of the Great Lakes. They like to breed in small streams branching off rivers, so they’re one of the most common types of salmon to be found in local creeks or neighborhood stream beds.