Why Do Seals Need Ice?

Seal on ice. Jaymi Heimbuch

For many marine mammals living near the poles, pack ice is of critical importance. It provides shelter and a place to rest near food sources. Without it, seals would have to travel great distances to reach any sort of a shoreline, a journey that would greatly weaken them and lower their chances of survival in an already unforgiving environment.

The ice is also a safer place to keep away from predators, which is particularly critical during pupping season. Many seals give birth to and nurse their pups on the ice, with the growing youngster staying on the ice while the mother hunts for food near the edge.

The National Snow and Ice Data Center notes: "Decreasing sea ice extent would reduce the habitat available to ringed seals. Early ice breakup could result in premature separation of mothers and pups, leading to higher death rates among newborn pups ... If autumn and winter are fairly mild, the ice is soft and thin and disintegrates easily. As a result, newborn seal pups, which are born on the ice, do not have enough time to wean properly and may not survive."

Meanwhile, adult seals also need the ice as protection from predators and a food source. Harp seals, for example, feed on small crustaceans and fish that hang out around the edges of sea ice — so less ice means less food.

There are six species of seal in the Arctic, and four species in the Antarctic. Of these, several species such as ringed seals, bearded seals and Weddell seals are particularly dependent on the ice; they spend their whole lives on or around it.

Such a dependence on ice is one reason why the bearded seal is now receiving federal protections, despite currently having a decent-sized population, since the species will be impacted by the future loss of sea ice due to climate change.