FILE - In this March 28, 2018, file photo, a North Atlantic right whale feeds on the surface of Cape Cod bay off the coast of Plymouth, Mass. Six of the endangered right whales died in the Gulf of St. Lawrence in June 2019, prompting scientists and conservationists to call for a swift response to protect the endangered species. (AP Photo/Michael Dwyer, File)
FILE - In this March 28, 2018, file photo, a North Atlantic right whale feeds on the surface of Cape Cod bay off the coast of Plymouth, Mass. Six of the endangered right whales died in the Gulf of St. Lawrence in June 2019, prompting scientists and conservationists to call for a swift response to protect the endangered species. (AP Photo/Michael Dwyer, File) Credit: Michael Dwyer

A half-dozen North Atlantic right whales have died in the past month, leading scientists, government officials and conservationists to call for a swift response to protect the endangered species.

There are only a little more than 400 of the right whales left. All six of the dead whales have been found in the Gulf of St. Lawrence off Canada, and at least three appear to have died after they were hit by ships.

The deaths have led scientists to sound the alarm about a potentially catastrophic loss to the population. The deaths are especially troubling because they include females, said Philip Hamilton, research scientist with the Anderson Cabot Center for Ocean Life at the New England Aquarium.

โ€œIf weโ€™re going to have deaths, they just canโ€™t be female,โ€ Hamilton said, adding the population is down to only about 100 reproductive females.

Right whales have suffered high mortality and poor reproduction in recent years, particularly in 2017. The whales appear to be traveling in different areas of the ocean than usual because of food availability, said Nick Record, senior research scientist at Bigelow Laboratory for Ocean Sciences in Maine.

That shift has apparently brought whales outside protected zones and left them vulnerable, he said.

โ€œAnimals like whales that have to figure out where their food is, they have to figure out a new environment as they go,โ€ Record said.

Fisheries and Oceans Canada said Tuesday that the necropsy of the sixth whale, which was named Clipper, was completed in Quebec and that the animalโ€™s death appeared consistent with blunt trauma from a vessel strike.

Ship strikes and entanglement in fishing gear are two top threats to right whales often cited by conservationists.

A speed restriction of 10 knots in the area where the whale was first observed remained in effect, the agency said. It also said it has increased surveillance over the Gulf of St. Lawrence to assess the location of the whales and make sure mariners comply with rules.

Chris Oliver, assistant administrator for the National Oceanic and Atmospheric Administrationโ€™s National Marine Fisheries Service, said Wednesday he is calling for a meeting with the Canadian government to request โ€œimmediate action to provide comprehensive protectionโ€ for the whales.

โ€œPreventing any additional deaths of North Atlantic right whales is our highest priority. To do this, we must work with our partners to strengthen protections immediately,โ€ Oliver said in a statement.