They reserve the vocal fry register for navigation. Able to dive to more than a mile underwater. Many of these whales hunt in near complete darkness. The animals use sound to find their way underwater sending out powerful pulses and listening to the echo in order to spot their food. Toothed whales rely on vocal fry to make the echolocation clicks. According to the study. Undersea the air is precious and whales likely evolved to use the lower register for echolocation since it uses air the most efficiently