CHURCHILL, Man. -- Manitoba conservation officials say late sea ice formation on Hudson Bay has lead to a record number of polar bear encounters with the people of Churchill.

Polar bears came too close to town almost 390 times this year -- a jump from 351 in 2015 and 229 in 2013. Some 53 bears were held in the town's so-called polar bear jail and all had been released by last week.

Daryll Hedman with Manitoba Conservation said the sea ice didn't form until well into December, leaving hungry polar bears crowded on the shore.

"They were sitting there waiting. There were some pretty big concentrations of males out there," he said. "Eventually the ice did come in.

"On record, this is the latest year ever."

Canada is home to two-thirds of the world's polar bears, but experts say climate change could make the Hudson Bay population extinct within a few decades.

Polar bears depend on winter hunting to build up enough fat to carry them through the lean summer months on land where food is scarce.

But Arctic waters freeze up later in the year and thaw much earlier in the spring. That leaves polar bears with less time to bulk up on fatty seal meat while on the ice.

As the bears spend more time on land with less fat, they grow hungry and can venture into town in search of food. Where the first encounters with polar bears used to be late August, conservation officials say polar bears are now coming into contact with people as early as July 1.

Every time officers get a call about a bear, they have to march it back to the wilderness. Nuisance, repeat offenders land in the polar bear jail where they are kept for 30 days before being released.

"This year, 2016 definitely was one of the busiest years that the staff up there have had," Hedman said.

Luckily, Hedman said the polar bears came off the ice in good condition which helped sustain them while waiting for the ice to form.

Andrew Derocher, one of the country's leading polar bear experts based at the University of Alberta, said there will likely come a year when the bears will come off the ice in poor shape and won't be able to survive until the ice freezes again.

"The longer the ice-free period is in Hudson Bay, the worse it is for the bears. Definitely, 2016 was getting out there," Derocher said. "We haven't really hit the critical thresholds for ice-free period or fasting period for the bears yet but we're certainly getting closer.

"We could see a catastrophic decline."

The increased number of encounters with polar bears might lead people to think that the population is booming, he said. In fact, he said the opposite is true. The number of Hudson Bay polar bears has dropped to about 800 from 1,200, he said.

"The population is declining but the number of problem bears is increasing," Derocher said. "What we're really looking at is a change in behaviour and a change in distribution.

"Bears think with their stomachs. That's a real problem when you get hungry bears around people."

By Chinta Puxley in Edmonton