Arctic walruses forced to choose: food or family?

WASHINGTON - Walruses in the Arctic face perilously long journeys between feeding grounds and haul-out sites as global warming melts the sea ice where the calves must remain to rest and avoid predators, according to the latest chapter of Defenders of Wildlife’s global warming series “Navigating the Arctic Meltdown.” Adult females must make longer trips between their shallow water feeding grounds and the sea ice floes where walrus calves rest, as the expanse of open water in the Arctic grows. Where the ice edge was formerly near the shallow-water feeding grounds, it now retreats in summer far out to sea, over waters too deep for the mothers to dive to reach the clams and other bottom-dwelling creatures they eat. In some cases, these huge mammals face a grim decision—follow the ice floes to deeper water and risk starvation, or abandon their calves on the ice floes while the mothers seek food further away in shallow-water feeding grounds.

“Abandoned and more vulnerable walrus calves are one of the starkest, most tragic consequences of global warming in the Arctic,” said Jean Brennan, senior climate change scientist for Defenders of Wildlife.

Not every case is as black and white as “food or family” yet, but across the board the warming temperatures are melting more ice each summer and allowing less ice to freeze each winter. In fact, the extent of sea ice was at a record low in mid-August of 2007, and sea ice will continue to melt through September. A lack of stable ice pack means that the calves on the sea ice are farther away from the feeding grounds where their mothers fill up on clams and mussels to produce the high-calorie milk to feed their growing young. This leads to long, exhausting swims for the mothers and more time when the calves are alone and vulnerable on the ice floes and in surrounding waters. Without their mothers rich milk, walrus calves cannot develop a thick insulating fat layer to withstand the harsh Arctic water temperatures.

“A rich food supply near the walrus’ home ice is critical to keep the mothers’ energy up while they nurse so this constant journey back and forth between feeding ground and ice floe is exhausting for the female and ultimately weakens both her and the calf,” said Brennan.

Walruses in the Atlantic Ocean have the option to haul out to rest and leave their calves on land because there are large clam and oyster beds fairly near the shores of Greenland and the Canadian islands. However, walruses are clumsy on land and much more vulnerable to bears and human hunters. In the Pacific Ocean, however, the richest feeding areas are located far offshore in the shallow seas, so the animals rarely have the opportunity to rest on land and rely almost exclusively on the ice floes as resting places. As global warming claims more and more ice, walruses must work all that much harder to survive.

In its series on global warming and the Arctic, Defenders stresses the need to reduce greenhouse gas emissions as a key to reducing the effects of global warming over the long term, both in the Arctic and worldwide. But in the meantime, adaptive measures must be taken to eliminate other pressures on species being negatively impacted by global warming, and to better understand what steps we can take to preserve arctic animals and plants.

First, countries should ensure that lands walruses use for resting are protected from commercial exploitation and enforce strict laws protecting walruses from illegal ivory harvest in these areas.

Second, the fishing industry and agencies that regulate harvests should consider the impact of commercial clam and mussel harvests, as these are the main source of food for walruses. Commercial pressure is mounting on clams and mussels in the north Atlantic and Pacific because of over-harvesting. The impacts of northward expansion of this industry into walrus habitat should be considered in light of the added pressure that global warming is putting on the Arctic and all of its inhabitants, including walruses.

Last, restrictions on off-shore oil and gas exploration will help walruses adapt to their changing environment. Exploration activities degrade mussel beds, may disturb walruses, and interfere with feeding, resting and rearing of walrus young. Oil spills also pose an ever-present danger that could severely impact the Arctic.

“While it may take 100 years or more to begin to reverse some of the harmful changes we’ve already caused to the Earth’s climate, it is our responsibility to step up our efforts to protect wildlife that is being affected by global warming today so our children and grandchildren will be able to enjoy wildlife tomorrow,” says Rodger Schlickeisen, president of Defenders of Wildlife.

The first nine chapters of “Navigating the Arctic Meltdown” and subsequent installments as they become available can be found at Global Warming.

###

Defenders of Wildlife is dedicated to the protection of all native animals and plants in their natural communities. With more than 900,000 members and activists, Defenders of Wildlife is a leading advocate for innovative solutions to safeguard our wildlife heritage for generations to come. For more information, visit www.defenders.org.