HALIFAX -- A new report says vessel strikes caused almost half the deaths of endangered North Atlantic right whales in the Gulf of St. Lawrence last year.

The report by the Marine Animal Response Society and the Canadian Wildlife Health Cooperative says necropsies were done on five of the nine whales found dead between June and July 2019.

Vessel strikes were found to be the most likely cause of death in four of the animals, while the cause of death of the fifth could not be determined.

Necropsies could not be performed on the remaining four whales and their cause of death remains unknown.

With only about 400 individuals remaining and the population in decline, the North Atlantic right whale is one of the world's most endangered large whale species.

In the last five years, 25 right whales have died in Canadian waters.

Tonya Wimmer, executive director of the Marine Animal Response Society, said efforts to study the whales and reduce threats to the population have fallen short.

"Recovery efforts for this species in Canada are not going in the right direction -- whales are still dying at an alarming rate and the population is in decline. More needs to be done," Wimmer said in a statement.

This report by The Canadian Press was first published June 24, 2020.