An expert on polar bears says he is not surprised by a recent sighting near the Hibernia oil platform.

On Monday, the crew on the Atlantic Merlin were amazed to see the bear swimming so close to the platform, which is located about 315 kilometres east-southeast of St. John's. 

Ian Stirling, an adjunct professor at the University of Alberta, said at this time of year, there are large numbers of harp and hooded seals offshore, and sometimes polar bears will leave sea ice in pursuit of their favourite prey.

Stirling said often the animals lose track of where they are.     

"I think this is probably a fairly regular event. It's not as common to actually see them," he told the St. John's Morning Show.

Polar Bear Risk 20110712

Ian Stirling says it's natural for polar bears to take the risk of pursuing seals farther offshore. On average, the animals can swim more than 150 kilometres at a time, depending on their age and weight. (The Canadian Press/Jonathan Hayward)

"It's like investing. It's really risky. One of those things, you might buy something, you win big — or you buy something and you lose big, and that's what's happened to this bear."

Stirling said polar bears start to feed on harp seals offshore and there are hundreds of thousands of them. 

"Some of the bears get out there — and they've never had it so good. And they [the seals] don't run away like a ring seal. But what they don't notice is that sometimes the ice, with a bit of wind, is blown out and goes out to Davis Strait — and all of a sudden they're far away from anywhere," he said.

Hibernia oil rig was bear's potential refuge

Stirling said depending on how far the animal has travelled, a lot of them probably won't make it.

He said a recent study completed in Alaska indicated that on average, a polar bear can swim more than 150 kilometres at a time, depending on their age and weight. Stirling said the bear that appeared near the Hibernia oil platform on Monday was fairly young, and not that large.

"It's well-known that animals can swim on average long swims,150 kilometres is what that they can handle. I think it's touch-and-go even if he went in a straight line, whether he'll be able to make it back to land at some point," said Stirling.

"If he could see the platform from a distance, he would have gone over to it to check it out as a place to climb out. That's what they do all over the Arctic," he said.

"If they're out on the sea ice and there's a small island or a rocky cape, they'll come in off the sea ice and head for those places. He was looking at that rig as a potential refuge."

Polar bears will keep swimming 

Stirling said the longest known swim for a polar bear is 687 kilometres.

"And that was done by a female that had a yearling when she started. She lost 22 per cent of her weight — and she lost her yearling," he said.

'But what they don't notice is that sometimes the ice, with a bit of wind, is blown out and goes out to Davis Strait — and all of a sudden they're far away from anywhere.' - Polar bear expert Ian Stirling 

Stirling said if a bear is in good shape, it can probably make it back, but the animal will lose a lot of weight in the process.

"These tracks have been monitored from bears with satellite radios on, so you know if they stop, you know whatever's going on. It looks like they don't sleep much, they generally keep going, especially if they started to lose some fat," he said.

"They no longer are buoyant like a fat seal, for example. So they really can't stop, they've got to keep going or keep moving to some degree, so they don't sink. With climate warming and ice getting into rougher shape and breaking up earlier and being less stable, I think in future years as that trend goes on, I think it's possible to see more like that."

With files from Julie Skinner