A clue has emerged in the hunt to find what is causing the horrific corkscrew injuries to many dozens of seals whose bodies have been washed up along Britain's east coast this summer.
The results of post-mortem examinations on the remains of 12 seals found in Norfolk have revealed the most likely cause of death to be a ducted propeller (which is non-rotating) from a ship.
More than 50 animals have been killed in Britain since the phenomenon was first observed. The mutilated bodies carry an unmistakable corkscrew wound in which the flesh is cleanly stripped from the body in a winding motion from the head downwards.
The main theories put forward so far include shark attack, wind farms and shipping. Callan Duck, senior research scientist at the Sea Mammal Research Unit at St Andrews University, which is investigating the deaths, said it was not known how many ships might have the propeller.
He urged boat owners that might have the propeller to come forward, adding: "We are not looking to point the finger at anyone. They are almost certainly unaware of it."