Right whales getting tinier:

One of the giants of the deep is shrinking before our eyes, a new study says.

The younger generation of critically endangered North Atlantic right whales are on average about three feet (one meter) shorter than whales were 20 years, drone and aircraft data show in a study in journal Current Biology. Scientists say humans are to blame. Entanglements with fishing gear, collisions with ships and climate change moving their food supply north are combining to stress and shrink these large whales, the study says.

Diminishing size is a threat to the species’ overall survival because the whales aren’t having as many offspring. They aren’t big enough to nurse their young or even get pregnant, study authors said.

These marine mammals used to grow to 46 feet (14 meters) on average, but now the younger generation is on track to average not quite 43 feet (13 meters), according to the study.

“This isn’t about ‘short’ right whales, it’s about a physical manifestation of a physiological problem, it’s the chest pain before the heart attack,” said Regina AsmutisSilvia, executive director of Whale and Dolphin Conservation North America, who wasn’t part of the study. “Ignoring it only leads to an inevitable tragedy, while recognizing and treating it can literally save a life, or in this case, an entire species.”