10/05/2017 08:01 EDT | Updated 10/05/2017 11:01 EDT

Scientists release results from probe into deaths of North Atlantic right whales

CHARLOTTETOWN — Veterinarians examining the carcasses of six right whales found dead in the Gulf of St. Lawrence this summer say four died from blunt force trauma, one was entangled in fishing gear and the other was too decomposed to say for sure.

Pierre-Yves Daoust of the Atlantic Veterinary College says there was no evidence to suggest various toxins may have played a major role in the deaths.

He told a press conference in Charlottetown on Thursday a seventh whale that was necropsied but not included in the report also showed signs of fishing gear entanglement.

About a dozen North Atlantic right whales have died in the Gulf since June — an unprecedented number of deaths for a marine mammal that is at risk of extinction with an estimated population of just 458.

Scientists say ship strikes and entanglements in fishing gear are the greatest threats to the slow-moving animals.

In August, the federal Fisheries Department announced new measures to improve the safety of whale migration in the Gulf, including rules around fishing gear and speed restrictions for large vessels.

"They died because of human activity," said Tonya Wimmer, director of the Marine Animal Response Society.

The focus now has to be about preventing ship strikes and entanglements, she told the news conference.

"Everyone really needs to sit down together -- all the players" from government, industry and animal protection in Canada and the U.S., Wimmer added.