PORTLAND, Maine — Federal researchers are sharpening their focus on the recent deaths of endangered North Atlantic right whales.
The animals are among the rarest marine mammals in the world, with only about 500 still living.
At least 13 right whales have been found dead this year off the coasts of New England and Canada, prompting the National Oceanic and Atmospheric Administration to declare the deaths an “unusual mortality event” and to launch an investigation.