Arctic cod

What it is

This fish has a slim body with a deeply forked tail and a small barbel on its chin. Its mouth projects forward, and it possesses three separate dorsal fins along with two anal fins. The pectoral fins extend past the first dorsal fin, while the pelvic fins are long rays. The lateral line runs in broken segments along its side. Colouration is generally silvery with brown spots, though some populations show lighter or darker variations. Adults typically reach twenty-five centimetres, with a maximum recorded length of forty centimetres.

Where it lives

It lives further north than any other fish, found across the entire North Polar Basin. Its range covers waters above Russia, Alaska, Canada and Greenland, including the Barents, Kara and Beaufort Seas. The species inhabits coastal zones, the mesopelagic layer and areas beneath sea ice. In winter and spring, it moves vertically through the water column, but stays at consistent depths during summer. Young fish stay near the surface, while adults dwell deeper than one hundred metres.

How it lives

As a keystone species, it transfers energy from zooplankton to larger predators. Seals, whales and seabirds rely on it as a primary food source due to its high lipid content. The fish eats plankton, krill and various amphipods. Larvae consume eggs and nauplii, while larger individuals may eat other fish. It accumulates fat reserves quickly in late summer to survive the low-production winter months. Schools often form near glacial fronts where freshwater plumes stun prey.

Breeding and life cycle

Females lay between nine thousand and twenty-one thousand eggs. Spawning happens from September to April, with peak activity in early winter. Eggs develop best in cold water between minus one point five and three degrees Celsius. Hatching success drops sharply if temperatures rise above two degrees. Larvae hatch under the ice and can tolerate varying salinity levels. Juveniles grow rapidly and reach sexual maturity at two or three years of age.

Fish and people

Commercial fishing by Norway and Russia ended in 2012 due to falling numbers. It is not a major subsistence food for Inuit communities but serves as bait for halibut fishing in Greenland. Fishers use sonar to locate schools and catch them with mesh nets. The species is often caught as bycatch in shrimp and halibut trawls. Its remote habitat and low market value prevent large-scale commercial exploitation today.

Status and threats

The Norwegian Red List classified it as highly threatened in 2021. Warming oceans reduce embryo survival rates and shrink sea ice habitats. Boreal species like Atlantic cod are moving north, increasing competition and predation pressure. Loss of ice cover exposes eggs to harmful ultraviolet radiation and turbulence. Noise pollution from shipping may also fragment their habitat and cause stress.

Relatives and look-alikes

It is often confused with Arctogadus glacialis, which also bears the name polar cod. Larval stages of both species look similar and require molecular analysis or otolith examination for accurate identification. It belongs to the cod family Gadidae and is related to the true cod genus Gadus.

Questions people ask about Arctic cod

Good reading and sources

• Boreogadus on WikipediaEncyclopedia
• More photos on Wikimedia CommonsPhotos
• Wikidata recordOpen data