Unexpected Porpoise Predators Revealed As Formidable Gray Seals



Your typical gray seal, Halichoerus grypus, a hunter of small cetaceans? (Source)

Following the regular discovery of mutilated harbor porpoise carcasses on Dutch beaches since 2003, a group of biologists began a ten year investigation into the situation's cause.¹ The usual suspects of boat propellers or hostile fishermen were dismissed after the deaths regularly continued their toll, and the enigma continued until a group of Belgian researchers came to a startling conclusion.¹ In 2012, these researchers took note of apparent bite marks present in some of the wounds inflicted upon the thousands of porpoise carcasses.¹ These matched the canine teeth of an unexpected yet certainly capable mammalian predator: the gray seal Halichoerus grypus. With bulls reaching up to almost eleven feet in length and weighing as much as 310 kilograms this was no huge surprise, especially considering their being relatives of animals like the formidable leopard seals. Further examination of the carcasses showed the marks of pinniped claws and signs of the seals having gone after the nourishment of a porpoise's blubber¹, yet the proposition was still subject to some debate.

Harbor porpoise carcass with wounds indicative of gray seal predation. (Source)