To answer your question, let’s focus on two species – walruses and beluga whales – to understand how changing ice conditions might cause Arctic marine mammals to change their movements or choice of habitats.
Walruses are considered by many researchers to be one of the species most threatened by loss of sea ice. They are specialized feeders that eat clams and other invertebrates on the seafloor in shallow water. Between periods of feeding they haul or get out of the water to rest, usually on sea ice. With less ice available during the late summer, walruses are now hauling out on land by the thousands. These new haulout areas can be farther away from where they feed, so walruses likely spend more energy getting to and from their ocean feeding grounds. That can mean less blubber stored up to get them through lean times or to nurse their pups.
Beluga whales are a different case. They can eat a wide range of prey from the ocean’s surface down to depths of more than 800 meters (about 2,600 feet). They also spend their entire lives in the water and don’t depend directly on the ice for survival. Less ice will mean a change in the availability of some prey species, but belugas are more likely than others to adapt to change. Researchers haven’t yet seen a change in the movements of belugas that relates to a reduction in sea ice.
Observing walrus movements is important because new haulout areas on land instead of ice could be critical refuges, necessary for the survival of the species. Belugas may also move into new areas as sea ice is reduced. Careful study of these animals’ behaviors and movements is imperative to try to prevent human activities from adding challenges for Arctic marine mammals at a time when each species must adapt to a changing environment.
— Josh Jones, staff research associate, Whale Acoustics Laboratory