The Critically Endangered North Atlantic Right Whales Are Shrinking

BOSTON (CBS) -- There are fewer than 400 North Atlantic Right Whales left on Earth, and new research shows that they are shrinking in size. According to aerial footage published in Current Biology, whales today are as much as 3 feet shorter as they were 40 years ago, and fishing gear entanglement is part of the problem.

"Entanglements in fishing gear and other factors are stunting the growth of North Atlantic right whales," the New England Aquarium said in a statement. "This is leaving these critically endangered whales smaller and more vulnerable to other threats."

In some "extreme examples," researchers said 10-year-old whales are shorter than a typical one 1 or 2-year-old whale. The calves of mother whales who become entangled while nursing are also turning out shorter.

Scientists used footage from airplanes and drones to study whale size. They believe other factors are also reducing whale size, including vessel noise and availability of the tiny plankton copepods that make up their diet.

"There is an increasing human footprint in the ocean, and it's likely a combination of several compounding factors that are affecting the growth and life history of these vulnerable animals," said Joshua Stewart, a researcher at NOAA Fisheries' Southwest Fisheries Science Center.