The International Union for Conservation of Nature is moving the whales from "endangered" to "critically endangered" on its red list of global species facing threats to their survival.

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.

DFO says a cluster of eight grids in the middle of the Gulf will be closed until November 15.

Fewer than 400 of the giant creatures are left, and ship strikes and fishing-gear entanglements have proven to be lethal to them.

NOAA identified the mom as 31-year-old Palmetto who last gave birth in 2009. This is her fifth calf.

It's believed there are now fewer than 90 breeding females, and deaths have outpaced births in recent years.

NOAA says that the calf appears to have injuries to its mouth, which could hamper its ability to nurse and feed. 

A Florida wildlife conservation team saw the pair seven miles from shore while doing routine aerial surveys of the right whale calving ground.

Phillip Hamilton, a research scientist at Boston's New England Aquarium, wasn't involved in the necropsy carried out on the whale but says it often takes up to a month or two to get lab results.

The area near Grand Manan Island has been closed to all fixed-gear fisheries, DFO announced in a tweet on Thursday.