POINTE-DU-CHENE, N.B. -- The federal government is ordering large vessels to slow down in the Gulf of St. Lawrence, as it tries to protect right whales who frequent the waters.

Ten of the endangered mammals have died in the gulf since early June -- at least some after colliding with ships.

Fisheries Minister Dominic LeBlanc and Transport Minister Marc Garneau went to Pointe-du-Chene, N.B., Friday to announce immediate temporary measures aimed at preventing further whale deaths.

Garneau said vessels of 20 metres or more will be required to slow to 10 knots -- or about 19 kilometres per hour -- while travelling in the western Gulf of St. Lawrence, from the Quebec north shore to just north of Prince Edward Island. The limits of that zone are subject to change, he said.

"These are reasonable measures to accomplish something very important," Garneau said. "I think that Canadians and the shipping industry and the fishing industry recognize that this is something most unusual and we need to take measures."

The measure will be enforced by Transport Canada and the Canadian Coast Guard. Ships that don't comply with the speed limit will be subject to a financial penalty of up to $25,000.

Smaller ships are being asked to voluntarily abide by the speed limit, which will remain in place until the whales have migrated from the areas of the gulf that pose the most concern.

The measure was designed in consultation with the fishing and shipping industries, who Garneau said have for the most part embraced the conservation effort.

"We do realize that there is some impact, but I think the marine industry also recognizes that we are trying to achieve something extremely important," he said.

Garneau said cruising speeds typically hover around 15 knots, on average, but faster vessels can reach up to 25 knots.

The speed limit is meant to reduce the frequency and fatality of ship strikes, he said.

Federal officials did their "homework" before deciding on the measure, the minister said, including working with their U.S. counterparts at the National Oceanic and Atmospheric Administration, which implemented similar speed restrictions in right whale habitats in 2010.

LeBlanc said the federal government has spent around $360,000 on performing necropsies, akin to animal autopsies, on six whale carcasses. He said the full results of these examinations are expected to be released next month.

Early findings suggest some of the whales died of either entanglements with fishing gear, or from blunt trauma caused by ship collisions.

It's believed 80 to 100 right whales are currently in the gulf, LeBlanc said, and scientists expect the mammals to migrate south some time this fall.

The Fisheries Department has already taken steps to prevent further deaths, including shortening the snow crab season and asking fishermen in the gulf to report any whale sightings.

LeBlanc said the existing measures will be continuously reviewed based on aerial surveillance of the whales' migration patterns. He said further steps may include temporary fishery closures, changes to fishing gear, and shipping lane adjustments.

The speed restrictions could lead to up to seven-hour delays for some voyages, according to the Ottawa-based Chamber of Marine Commerce, but president Bruce Burrows said industry stakeholders are committed to protecting marine life.

"These recent whale deaths are deeply troubling for our members too," Burrows said in a statement. "It's critical that industry and government continue to work closely together to develop solutions based on strong science that both protect marine wildlife and minimize economic impacts."

The chamber, which represents around 130 marine industry stakeholders, said ship owners are assessing how the measure will affect deliveries and passenger trips along Quebec's north shore.

Burrows said ship owners have hewed to voluntary protection measures when possible and urged the federal government to "accelerate" its analysis of the right whale deaths.

A spokesperson for Oceanex, a Newfoundland-based shipping company, declined to comment on the matter Friday. But Oceanex's Sid Hynes told CBC last week that speed reductions could have "huge" financial consequences for his fleet -- and that cost would be passed on to consumers.

Moira Brown, a right whale expert with the Canadian Whale Institute, said compliance will be key to preventing further losses, but industry has proved to be a willing partner in the past.

"There's a very positive reaction on the part of some (ship owners), and I've heard some things about feeling it was going to cost more money," Brown said in an interview. "It's going to take a little time to get used to this idea and adjust their voyage planning in order to compensate for it."

In a statement, the World Wildlife Fund Canada called the speed restriction a "good start," but said permanent steps to protect the whales' habitat are required.

It's estimated there are only about 500 North Atlantic right whales alive.

--By Adina Bresge in Halifax