Polar cod have huge appetites. When large schools of polar cod get together, they can sometimes feed so aggressively that they cause local depletions of zooplankton. But by ingesting all that food, polar cod grow large enough to serve as a high-energy food source for seabirds and Arctic marine mammals like ringed seals, narwhals and beluga whales.
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Status and Conservation
Unfortunately, this dependence on sea ice poses problems. The Arctic is warming more than twice as fast as the global average because of climate change, and sea ice habitats are rapidly disappearing. Failure of sea ice formation can cause huge problems for polar cod. Diminishing sea ice habitat makes it harder for them to reproduce, which decreases their numbers overall. This, in turn, affects all other species that rely on polar cod for food. Additionally, as water temperature warms in the Arctic, sub-Arctic species will be able to move northward and compete with polar cod for food.
One thing is for certain: without polar cod in the food chain, the Arctic ecosystem would be drastically different.