Life History and Habitat
Life history, including information on the habitat, growth, feeding, and reproduction of a species, is important because it affects how a fishery is managed. Very little is known about the habitat requirements of Pacific cod, particularly during their early life stages. More research to define nursery areas utilized by Pacific cod is one step being taken by fisheries scientists to further identify essential habitat and to monitor growth, survival, and subsequent recruitment to improve management efforts.

Geographic range: In the North Pacific Ocean from Port Arthur, China, in the northern Yellow Sea, north around the Pacific Rim into the Bering Sea as far north as the Chukchi Sea, and south along the North American coast to Santa Monica Bay, California. Also found off the east coast of Japan from Tokyo Bay to northern Hokkaido, on the west coast of Japan in the Sea of Japan, and off the coasts of the Sakhalin and Kurile Islands. Pacific cod are rare in the southern part of their range.
Habitat: Cod are demersal, living near the bottom, and concentrate on the shelf edge and upper slope (328 to 820 feet deep) in the winter and move to shallower waters (less than 328 feet deep) in the summer. Pacific cod have been found as deep as 2,871 feet. Adults and large juveniles prefer mud, sand, and clay habitats.
Life span: Relatively short-lived with a maximum age of about 19 years
Food: Clams, worms, crabs, shrimp, and juvenile fish
Growth rate: Moderately fast growing
Maximum size: Over 6 feet
Reaches reproductive maturity: Females mature at a length of 1.6 to 1.9 feet and at about 4-5 years of age.
Reproduction: Females have high reproductive potential – a mature female can produce over 5 million eggs. Pacific cod are single batch spawners, releasing all of their ripe eggs in a single spawning event within a few minutes.
Spawning season: From January through May, depending on location
Spawning grounds: On the shelf edge and upper slope (328-820 feet deep)
Migrations: Individual adults have been found to move more than 621 miles. Pacific cod also move seasonally from deep outer and upper shelf spawning areas to shallow middle-upper shelf feeding grounds. They are a schooling fish.
Predators: Predators include halibut, sharks, seabirds, and marine mammals.
Commercial or recreational interest: Both
Distinguishing characteristics: Pacific cod are brown or grayish with dark spots or patterns on the sides and a paler belly. They have a long chin barbell (a whisker-like organ near the mouth like on catfish) and dusky fins with white edges.


Role in the Ecosystem
Pacific cod are an abundant fish resource within the Pacific and North Pacific Oceans and the Bering Sea. The removal of Pacific cod by fishing may affect the food chain by reducing the amount of Pacific cod available as prey to predators, as well as reducing predation pressure on species that Pacific cod eat. Another consideration is the effect that bottom contact gear may have on living structure.

Pacific cod is a major prey item for endangered Steller sea lions. There are concerns that the Pacific cod fishery depletes important sources of prey for Steller sea lions, as much of the area used by the fishery is designated as critical habitat for the endangered sea lion (because of the prey resources available within it). One objective of Pacific cod fishery management regulations is to minimize competition between locally intense fisheries and Steller sea lions.



Additional Information
Market names: Cod, Alaska cod
Vernacular names: Alaska cod, Grey cod, True cod, Treska
Other species are also marketed as cod.