Walruses: Surprisingly sensitive
1 May 2017
Despite occurring over a vast area and having healthy population sizes in many regions, walruses face an uncertain future. MELANIE LANCASTER and TOM ARNBOM look at conservation actions to safeguard walruses from threats to their survival.
Pacific walruses (including the divergent Laptev walrus group) have a global population size of over two-hundred thousand and Atlantic walruses number around twenty five thousand. That sounds quite healthy, doesn’t it? Why then, you might ask, are we concerned about their future survival? Because, according to experts, all climate scenarios anticipate drastic changes to sea ice habitat in the Arctic, and this will eventually cause walrus populations to decline throughout their range. For this reason, they have been listed as Vulnerable on the International Union for Conservation of Nature (IUCN) Red List, and are a focus of conservation efforts across many organisations.
Conservation actions are not “one size fits all”, and Pacific, Atlantic and Laptev walruses are experiencing the effects of a warming Arctic in subtly unique ways. Pacific walruses spend spring and summer feeding over the huge, shallow continental shelf in the Chukchi Sea, north of Russia and Alaska. Mothers with calves rely on ice platforms over the shelf for giving birth and resting between dives to the seafloor. In recent years, sea ice has drifted hundreds of kilometres north of the shelf earlier in summer. This has forced walruses to come ashore along coastlines to rest in huge, crowded groups of tens of thousands of animals in Russian Chukotka and Alaska. From these coastal haulouts, they must travel farther to reach rich feeding grounds and are prone to being crushed in stampedes if they or their neighbours are suddenly startled. Thousands of walruses have been killed in stampedes, and walrus calves are particularly vulnerable.
In contrast, walruses in the Atlantic Ocean seem to prefer to rest on land, rather than ice. The reason for this difference is likely because the continental shelf of the Atlantic Ocean is much narrower and most feeding grounds in the Atlantic are often islands or closer to land. In the short term, walruses in the Atlantic should still be able to reach existing feeding grounds, and the loss of sea ice could even open new feeding areas for them.
Laptev walruses are different yet again. Along the Russian Arctic coast is the Laptev Sea where the Atlantic and Pacific walrus populations meet. In summer, walruses here seem to have adapted to live with no summer sea ice to rest and hunt from, hauling out on land to rest. However, these resting sites attract polar bears, which feed on walrus calves.
What conservation actions can we take to ensure the future for walrus? Undoubtedly, the most urgent and impactful conservation action the world can is to reduce global greenhouse gas emissions.
But several other threats face walruses and need addressing. The lengthening ice-free period in the Arctic brings greater opportunity for industrial development including shipping, mineral exploration and extraction, commercial fishing and infrastructure builds such as housing, harbours and airports. Best management practices through voluntary or regulated measures can be put in place to reduce harmful impacts of industry on walruses. Impacts include underwater and atmospheric noise (e.g. ship engines, seismic surveys), sea ice break up, direct disturbance and bycatch of walruses. In addition to incidental catch of walruses in fishing nets (bycatch), bottom trawling fisheries can destroy the sea floor and the fragile feeding grounds of walruses, who rely on mussels for their main food base. Identifying and safeguarding walrus haulout and feeding areas is another measure to protect them.
Temporary closures during particularly vulnerable times of the year and “no-go” zones are approaches that have worked to safeguard walruses hauled out onshore in eastern Russia. Another tool to reduce disturbance of these surprisingly sensitive giants is ship re-routing.
This strategy is used successfully to protect harp seal pupping grounds in the White Sea using daily satellite images of seal locations, which inform shipping routes through the area.
Regular monitoring of populations and understanding population boundaries is essential for ensuring a sustainable walrus harvest. Walruses have been hunted for subsistence purposes for centuries by Arctic peoples.
They are culturally important to Indigenous traditions, they are harvested for their meat with the sale of their ivory tusks and ivory crafts is an important source of income for Arctic communities. Overhunting is recognised as a potential threat to walruses, but is governed through responsible comanagement systems in most countries with legal hunting.
Monitoring of walruses is ideally done through a combination of scientific research and traditional/local knowledge. Healthy walrus populations are vital to Arctic people, but the Arctic’s remoteness means that monitoring can be challenging. Knowledge from local hunters is therefore hugely valuable for detecting changes in population distribution, body condition and health of walruses, and can provide early warning of broader ecosystem changes. In a warming Arctic, this is more important than ever to ensure the survival of this valuable natural resource and ecological asset into the future.
Senior Advisor, Arctic and marine
Senior Specialist, Arctic species
WWF Arctic Coordinating Team
Pacific walruses are segregated by gender for much of the year. Adult females and young follow the ice edge as it recedes through the Chukchi Sea in summer and they return to the Bering Sea in winter, while most males stay in the Bering Sea year-round. XAVIER MOUY says studies are underway to assess the effects of industrial activities on walruses.
Counting walruses is difficult, complex and labour intensive usually requiring repeat visits to haulout sites. Even then there are numerous variables swaying the numbers. MIKE HAMMILL says good record keeping is integral to good management of declining herds.