Canada's annual seal hunt has begun, amid international appeals for an end to the controversial cull.
Protestors say they are determined to stop the hunt next year
Up to 325,000 young harp seal pups could be killed in the coming weeks.
Celebrities such as former Beatle Sir Paul McCartney and his wife have joined animal rights groups in condemning the cull as barbaric and unnecessary.
Prime Minister Stephen Harper said Canada was victim of an "international propaganda campaign", and insisted the cull would be carried out humanely.
Found in north Atlantic and Arctic oceans
Feed on fish and crustaceans and spend much of year at sea
Pups born on the ice and nurse for two weeks, after which their mothers abandon them
Can be legally hunted only once their white coats darken, at about two weeks old
The cull, which reportedly earns C$16.5m (£8.3m) in meat and pelt sales, is an important source of income for fishing communities in Quebec and Newfoundland that have been hit hard by dwindling fish stocks in the Atlantic.
The hunt is "an annual harvest and it is based on economics... It is harvesting animals on a sustainable basis", Roger Simone of the Department of Fisheries and Oceans told the BBC.
The Canadian government says the cull is also necessary to control seal numbers, saying the seal population is now almost six million, nearly triple the level of the 1970s.
It recently increased the total allowable catch by 5,000, to 325,000 seals.
The first stage of the cull has begun in the Gulf of St Lawrence region in Quebec.
Some 90,000 seal pups in the area are expected to be killed before the hunt moves on to Newfoundland, where thousands more will be culled.
On the first day, sealers and protesters came face to face, sparking confrontations.
At one point, a sealer flung the carcass of a skinned seal at an inflatable craft carrying protesters and journalists.
"They threw carcasses at our Zodiac and they came rushing at us in their boat and tried to capsize us in the wake," Rebecca Aldworth of the Humane Society of the United States told the AP news agency.
Canada says it will not stop the controversial hunt
"This is standard behaviour out here. The sealers feel that they're completely above the law."
But the sealers say they are misunderstood.
Mark Small, president of the Northeast Coast Sealers Cooperation, has been sealing in Newfoundland waters for about 40 years.
"I think the Canadian public realises these are coastal people who live off the sea and depend on the hunt to survive in small communities where the fish stocks are not there," he told AP.
"Coastal communities have to live, too."
'Shut the hunt'
The head of the International Fund for Animal Welfare (Ifaw), Fred O'Regan, said in a statement that the cull was a "cruel hunt for products that nobody needs".
"Canada is better than this. It's time for the new Canadian government to shut down the seal hunt," he said.
Ifaw has asked the Canadian government to cancel this year's hunt due to poor ice conditions, which it says means many pups will drown anyway.
Sir Paul and Heather McCartney, who visited the region earlier this month to protest against the cull, made a last-minute video appeal.
"We are absolutely committed to making sure this is the last slaughter of baby seals in Canada anyone will ever have to witness," Sir Paul said.
They urged Canada to consider a "win-win" plan to end the hunt while compensating fishermen for lost revenue.
Celebrity campaigner Brigitte Bardot also asked the Canadian government to halt the cull earlier this week.
"Canada is a rich country. It doesn't need to sell skin, oil, fat and powdered seal penises to make aphrodisiacs for countries in Asia... You cannot continue a genocide of animals like this," the 71-year-old actress said.
But Mr Harper, who refused a request to meet Bardot, dismissed the suggestion.
"We don't harvest the pups," he said, referring to a 1987 ban on the killing of newborn seals with white coats pictured in many anti-hunt posters.
"Unfortunately, we're to some degree the victim of a bit of an international propaganda campaign... We believe the country is acting responsibly and we'll make sure all rules are enforced."