Whale researchers believe they have found a new way to help protect the animals from dying off. The researchers say they can study the mouths of dead whales to identify how often they faced serious threats, such as being hit by a ship. American Rosalind Rolland is the lead scientist on the project. She and her team are with the New England Aquarium in Boston, Massachusetts. They reported their findings in the online publication Marine Mammal Science. Rolland and her team studied baleen, a substance found in the upper part of the mouth of some kinds of whale. She explains that the baleen records each time the animal’s stress hormone increases. Scientists can then read these records, similar to reading the rings on a tree. Understanding the information is important because whales who often feel stressed are less likely to reproduce and more likely to become sick. That combination is not good for the whale population, which is already dangerously low.