FREDERICTON - The Canadian government is set to announce details of this year's East Coast seal hunt amid warnings of an ecological disaster on the unusually thin ice of the Gulf of St. Lawrence.

Fisheries officials will announce long-awaited plans for the annual harp seal hunt, including total allowable catch, from Ottawa on Thursday.

There is speculation the hunt may be scaled back due to poor ice conditions in the southern part of the Gulf, the area where anti-sealing groups and other observers traditionally watch the annual slaughter.

The International Fund for Animal Welfare and the Humane Society of the United States are calling for cancellation of the entire seal hunt this year, including the largest part of the hunt off Newfoundland and Labrador.

"This is one of the worst ice years on record,'' said Rebecca Aldworth of the humane society.

"We can't see how a responsible government would allow a commercial hunt to go ahead under these conditions.''

Aldworth estimates as many as 260,000 harp seal pups may have been lost as thin ice on the Gulf broke up and drifted into the open ocean.

Newborn pups cannot swim during their first three weeks of life and need thick ice to survive.

"This is a very serious ecological disaster,'' she said in an interview. "Those pups are not old enough to survive in the water.''

Mike Hammill, a research scientist with the federal Fisheries Department, said much of the ice in the southern Gulf has broken up and moved into the ocean.

"I think pup mortality will be higher than normal,'' he said.

"We have been anticipating this in our modelling the last few years. We have been putting into our model the assumption that we're losing 100,000 extra pups due to poor ice conditions. ...  I think the numbers will be higher, but I'm not sure how much higher. It's not an ecological disaster.''

Hammill said the last seal population census in 2004 estimated the East Coast harp seal herd at about 5.8 million animals.

He said that number likely is down to about 5.5 million -- still a healthy size.

The seal hunt is expected to continue as usual in the northern Gulf and in the area called the Front off northeast Newfoundland. The Front is the largest part of the hunt, responsible in past years for least 70 per cent of the total catch.  Last year's total quota was 335,000 seals.

Hammill said there is no way of knowing whether the poor ice in the Gulf over the past few years is the result of global warming or part of a natural cycle.

He said ice conditions in 1969 and in 1981 were worse than this year.

"These things seem to operate on 10-year cycles,'' Hammill said.

But the International Fund for Animal Welfare said in a statement that the ice deterioration is here to stay and should be factored into the Canadian government's plans for the seal hunt.

Last year's hunt was one of the most turbulent in decades.

Clashes between sealers and hunt protesters in the Gulf of St. Lawrence, Quebec and Newfoundland highlighted growing tensions between the people who want to stop the slaughter of young seals and those who rely on it as a much-needed source of income.

The hunt also drew more international attention than usual when music superstar Paul McCartney ventured onto the ice with his then wife, Heather, to call for an end to the annual slaughter.