Researchers say the first right whale seen in the Gulf of Mexico in more than 20 years and her calf were recently spotted in waters off Cape Cod.
Female right whales travel to southern waters in winter, when they deliver calves. They typically stay in the Atlantic Ocean off the Florida and Georgia coasts before heading back north.
But this whale, who has been nicknamed Derecha, which means "right" in Spanish, was filmed swimming with her calf in Gulf waters in early April.
Right whales have head markings that are as unique as fingerprints. They include a wavy ridge on the whales' lower lips and callosities that look like white patches.
Beth Pike works on the New England Aquarium's right whale team that spotted the whales on Memorial Day. She says researchers matched the pair with "99.99 percent certainty," based on the calf's chin callosities.