Do Arctic Cod Eat Krill? And What They Really Eat

The Arctic Ocean, a perpetually cold environment, is home to a diverse range of marine life, including the Arctic cod (Boreogadus saida). This fish species thrives in the harsh conditions of the high latitudes. Arctic cod are widely distributed across the circumpolar Arctic, inhabiting waters that can be below freezing due to their unique physiological adaptations, such as antifreeze proteins in their blood. They are considered one of the most abundant and widespread fish in this region.

Do Arctic Cod Eat Krill?

Arctic cod can consume krill, but these are not typically the primary or most significant food source for adult cod. While krill can be a component of their diet, particularly for smaller or juvenile cod, their consumption is opportunistic and dependent on prey availability. Juvenile Arctic cod may feed on krill larvae or smaller krill species when other preferred prey are scarce. Their diet varies based on their size, region, and local food availability, allowing them to switch prey if usual food sources become limited.

Beyond Krill: Other Arctic Cod Prey

Arctic cod are generalist feeders, primarily consuming plankton and other small crustaceans. Their main dietary components include various copepods, such as Calanus species, which are lipid-rich zooplankton. Calanus glacialis is a dominant copepod in the Arctic and an important food source for Arctic cod, transferring energy from marine algae through the food web.

Amphipods also form a significant part of the Arctic cod’s diet. Gammariid amphipods, dominant fauna on the underside of Arctic sea ice, are consumed by Arctic cod.

The diet of Arctic cod shifts depending on their life stage. Small cod (4-6 cm) primarily eat copepod eggs and larvae. Intermediate-sized fish (8-12 cm) consume copepods, amphipods, and euphausiids. Larger cod (over 12 cm) continue to feed on copepods and amphipods, and can also consume arrow worms, and sometimes even smaller cod.

Arctic Cod’s Role in the Food Web

Arctic cod hold a significant position within the Arctic marine food web. They act as an important link, transferring energy from zooplankton to higher trophic levels. Biologists consider them a “gateway” species because they efficiently channel energy between different positions in the food chain. Arctic cod are the largest consumers of zooplankton in the Arctic.

Numerous predators depend on Arctic cod as a primary food source due to their high lipid concentrations. These predators include marine mammals like narwhals, beluga whales, and ringed seals. Seabirds, such as thick-billed murres, black-legged kittiwakes, and northern fulmars, also rely heavily on Arctic cod. The abundance and health of Arctic cod populations are closely tied to the survival of many Arctic predators.

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