HALIFAX -- A necropsy on the sixth North Atlantic right whale found dead this year suggests the mammal died after colliding with a vessel, officials said Tuesday.

The whale, known as Clipper, was found dead on Thursday, drifting off the Gaspe Peninsula. Fisheries and Oceans Canada said the necropsy on the mammal was completed Monday in Quebec.

"The veterinary team's preliminary conclusions are compatible with death due to blunt trauma, consistent with vessel strike," the federal agency said in a statement. "The speed restriction of 10 knots implemented by Transport Canada in the area where the whale was first observed is still in effect."

The results come after the Fisheries department said last week that another whale -- the third of the six found dead this year -- had also died after colliding with a boat.

More detailed results from both necropsies are expected in the coming months.

Meanwhile, officials said an entangled right whale seen on Saturday has not been seen again but aerial surveillance to locate it continues.

There are about 400 North Atlantic right whales left, with deaths outpacing live births.

None of the species were found dead in Canadian waters last year, according to Fisheries and Oceans Canada, after new measures were taken to protect the whales.

The measures included season-long fishing closures, temporary closures when whales are sighted and mandatory reporting for lost fishing gear.

Right whales come to Atlantic Canadian waters to feed on prey and they are usually present in the spring, summer and fall.