Arctic Cod

The Arctic cod, or polar cod (Boreogadus saida), is a small, cold-adapted member of the cod family (Gadidae) and one of the most important fish species in Arctic marine ecosystems. Found circumpolarly across the Arctic Ocean and adjacent seas, it is uniquely adapted to life at and beneath sea ice, tolerating water temperatures at or below the freezing point of seawater. Arctic cod occupy a pivotal ecological position, converting energy from zooplankton into a form accessible to a huge range of Arctic predators, from seabirds to seals and whales. Its abundance and central role in Arctic food webs make Arctic cod one of the most ecologically significant fish species in polar marine systems worldwide.

Arctic cod are small, slender fish adapted to icy polar seas.

• Body: elongated, slender, laterally compressed
• Color: silvery-brown to olive above, silvery below, sometimes with faint dark speckling
• Fins: three dorsal fins, two anal fins, deeply forked tail (more forked than most Gadidae)
• Barbel: tiny or absent chin barbel
• Size: typically 15-25 cm, rarely over 40 cm

Arctic cod are distinguished from Greenland cod by their much smaller size, more deeply forked tail, and minimal or absent chin barbel, and from saithe by their small size and close association with sea ice.

Arctic cod occur circumpolarly throughout the Arctic Ocean and adjacent seas, including waters around Svalbard, Greenland, northern Canada, Alaska, and Siberia. They are closely associated with sea ice, often found directly beneath ice floes as well as in open water down to several hundred meters. Arctic cod tolerate water temperatures near the freezing point of seawater, aided by natural antifreeze proteins in their blood, and can be found from the surface down to around 400 m. They favor cold, ice-covered or ice-adjacent waters over both continental shelf and deeper basin habitats, making them uniquely suited to the harshest marine environments on Earth.

Arctic cod form dense schools that shelter beneath sea ice, using the underside of ice floes as both refuge from predators and a feeding ground rich in ice-associated zooplankton. They feed primarily on copepods, amphipods, and other small crustaceans, and undertake vertical migrations tied to light and ice conditions. Spawning occurs in winter under ice cover, with eggs developing slowly in near-freezing water before hatching in spring. Arctic cod grow slowly and have a relatively short lifespan for the family. As the dominant forage fish of the Arctic Ocean, they form the primary prey base for narwhals, seals, Arctic seabirds, and other ice-associated predators, making them a keystone species in polar marine food webs.