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Last Updated: Monday, 14 May 2007, 21:34 GMT 22:34 UK
Answers to your walrus questions
Scientists want to find out where the walruses are migrating
A Greenlandic-Danish team of researchers has attached satellite tags to walruses in west Greenland.

Over the coming months, they hope to uncover the mystery of where this population migrates to over the summer months.

Erik Born, a biologist at the Greenland Institute of Natural Resources and the project's lead researcher, answers your questions.

How much do these animals weigh? Vaidehi Dhavde, Croydon, UK

Pacific walrus (M.V.Jensen)
Pacific walruses are heavier than the Atlantic sub-species
EB:There are two sub-species of walruses: Atlantic and Pacific walruses. We have tagged Atlantic walruses. Males weigh on average about 1,200kg (2,600lb), while females weigh about 800kg (1,700lb).

But the heaviest Atlantic walrus I have encountered was an adult male that had a total body mass of just over 1,600kg (3,500lb)!

Pacific walruses, which can be found around the Bering Strait in Alaska, are even bigger. They can weigh more than 2,000kg (5,000lb).

Why were the Atlantic walruses chosen to research rather than the other sub-species? Anna Hoover, Seattle, US

EB: The study is a joint initiative between the Greenland Institute of Natural Resources and the Danish Natural Environmental Research Institute, and we are hoping to provide the Greenlandic and Danish authorities with more information about the animals in their waters.

One of the things the tagged animals help us to find out is whether the current level of hunting that is taking place is sustainable.

There are indications that it is not, and has not been for several decades.

The tags will help us to look at this because they should tell us whether these walruses are a separate population, or whether they are meeting up with another population of walruses over the summer months.

If it turns out that walruses in Greenland are part of a larger population then the situation may be less worrisome.

Which satellites are being used to relay the data back to the monitoring team? Alan Webb, France

EB: We are using the Argos satellite system to see where the walruses are moving. This system is used for everything from keeping track of weather buoys to following animal migration.

Each time a tagged walrus surfaces, it connects to the satellite system and then this data is sent to a database that we can access.

What measures are in place to protect walruses from poaching? Dan Carlson, Rehovot, Israel

Walrus meat
Walruses are hunted for their meat in Greenland
EB: In different areas there are different measures to protect Atlantic walruses.

In the western Russian Arctic, walruses are pretty well protected; in Svalbard, they are completely protected; and on the east coast of Greenland, they are almost completely protected because they are located in the national park where hunting is prohibited.

But elsewhere in Greenland and in Canada they are hunted.

And in central west Greenland, where we have tagged the walruses, there is a comparatively high catch.

In 2006, the Greenland authorities introduced catch quotas and now only licensed hunters can catch walruses. This is enforced by local game officers and police. According to the legislation, illegal poaching is illegal.

Is there thought to be any walrus population movement between Svalbard and north east Greenland? Stella Maru, Brighton, UK

EB: Genetic studies indicate that there is very little exchange between walrus stocks in east Greenland and Svalbard. Satellite tagging carried out in these areas seems to support this.

However, a male walrus that we tagged in north east Greenland in 1989 was found three years later in north-west Spitsbergen, Svalbard. This is the only documented case of a movement of walruses between the two areas.

How long has the walrus been around? Kel Moreton, Lumphanan, Scotland

Walrus-like animals evolved about 10 million years ago
EB: Walrus-like animals evolved about 10 million years ago in the Pacific Ocean region. According to one theory, a group of these animals remained in these parts until they finally died out.

Another group spread out to the east via a channel called the Panamanian seaway between the North and South Americas to the North Atlantic.

About 600,000 years ago, descendants of the North Atlantic group wandered back again into the Pacific region via the Polar Ocean.

Because of the great distance between the seas in the Arctic, the groups became isolated and the walruses evolved into the current sub-species: the Pacific walrus and the Atlantic walrus.

What age do walruses live to? Kel Moreton, Lumphanan, Scotland

EB: In captivity, they live to about 45 years of age, but in the wild they live for about 35 years. Walruses are typical of large mammals: they live for a relatively long time, and have a slow reproduction - females give birth to calves every three years.

Isn't it better to let the mystery continue than to tell the world where these animals retreat to and have hunters and sight-seers disturb them? Christine Fowler, Los Angeles, US

EB: From aerial surveys and local knowledge, we know where walruses are in winter and summer - and local hunters and sight-seers have access to the same information.

But what we do not know, and are trying to find out, is where the walruses that winter in west Greenland go to spend the summer. Do they go west to Canada or north to north-west Greenland? We want to see which walrus groups are connected with which.

Are these animals threatened by climate change? Sarah Neumann, Winchester, UK.

Global warming means the pack ice is receding north
EB: I have a theory that climate change may not be as bad for the walruses of west Greenland as it definitely will be for polar animals such as ringed seals and polar bears.

If there is no ice, these animals are able to haul out on land. And their feeding areas are reasonably close to land, so perhaps they might not be so badly affected.

However, if they begin to use haul-out on land more frequently, then they must of course be protected on these haul-outs. Recently, walruses became completely protected on land in Greenland.

But I think the situation is different for Pacific walruses.

Each spring, thousands of walruses are moving north through the Bering Strait. And as they do this, they like to haul out on ice floes over their shallow feeding banks.

But because of global warming, the polar pack-ice edge is moving further north over deeper waters, where the walruses are unable to feed because the molluscs and clams that they like to eat are confined to shallow depths. And this could affect the walruses negatively.

Walrus distribution (BBC)
It is not clear whether the Laptev walrus is a separate subspecies

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