These huge marine mammals are found in the far north, typically hauled out on ice when resting between their long but shallow dives for clams and other mollusks on the sea floor. Lately, there has been so little summer ice that it is causing serious trouble for walruses. But why is the ice so important to them?
USGS explains, "Sea ice provides walruses with a resting platform, access to offshore feeding areas, and seclusion from humans and predators. The constant motion of sea ice transports resting walruses over widely dispersed prey patches." Without the sea ice, it is harder for walruses to get to new feeding grounds, and it requires them to travel long distances between feeding grounds and resting places, causing them to use up their hard-earned energy stores.
It's not just the walruses that need the sea ice - their prey populations need walruses to have that ice too. Walruses have a huge effect on the ecosystems in their feeding grounds, as they root along the sea floor churning up sediment and eating large quantities of prey. Without the ability to move around, they can exhaust an area of its food sources. When walruses are forced to haul out on land, the nearshore prey populations face significant pressure as more walruses feed in these areas.
Right now, the USGS is using satellite tags to track walruses in the Chukchi Sea to find out more about how the sea-ice retreat is affecting walruses and their prey sources. By better understanding their movements and where they are feeding, the researchers can learn more about the survival odds of the species on our warming planet. It will also help to provide insight for conservation planning, since the main feeding areas for walruses overlap with oil and gas lease blocks administered by Bureau of Ocean Energy Management.
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