2017 was the deadliest year on record for North American right whales since they became a protected species over 80 years ago. Through the summer, 15 right whales were discovered dead - most in the Gulf of St. Lawrence. This magnificent and mysterious animal is already facing extinction with fewer than 500 of the species left in the world. So researchers decided to autopsy the bodies to determine what's killing them.

From the Curio channel: News in Review.