The McCartneys arrived with two dozen reporters in four helicopters on the ice floe Thursday off the coast of the Magdalen Islands in the Gulf of St. Lawrence to shine a spotlight on Canada's annual seal cull.
"For many years, people have been trying to have this brutal practice stopped. We're out here to see if we can lend our voice to this campaign and maybe to get it stopped once and for all," said Paul McCartney, shivering in temperatures well below freezing.
Each year, some 300,000 seals are clubbed to death, earning $16.5 million Canadian ($14.6 million U.S.) in commercial meat and pelts for thousands of local hunters.
McCartney called the hunt "cruel."
"They say we've been doing it for 500 years, but that doesn't make it justifiable," McCartney said.
During a scrum with photographers, he and his wife lay down on the ice to caress a feisty, whining pup while an angry mother seal circled.
At one point, the pup snapped at a surprised Heather McCartney while a helicopter pilot hired by the U.S. Humane Society kept the mother at bay with a walking stick normally used to check ice stability.
Canadian regulations prohibit the harassment of seals. Violators face a fine up to $100,000 Canadian ($85,000 U.S.), but minor infractions are usually ignored, officials said.
Last year, 11 activists were fined $1,000 Canadian ($850 U.S.) for interfering with the March seal hunt after an altercation with hunters while trying to document the harvest.
Their lawyer said recently they would opt for 22 days in jail rather than pay the fine and planned to hold a hunger strike during their incarceration, the local
Guardian newspaper reported.