morwennol replied to your photo:Bingo card for things that I thought would come up...
Okay. This is not what the Sea Mammal Research Unit call them. But...
For a few years now there has been a spate of seal carcasses washing up with strange corkscrew-like injuries, and it's been a bit of a mystery. Theories include that they've been dragged through a ducted propeller (like those used for positional thrusters on offshore construction vessels); or that someone has been laying traps on the seabed (that's the more out-there of the theories)... But generally, it was thought they couldn't be natural because the injuries were too weird and regular, almost surgical.
However recently new evidence has come to light that, contrary to what was thought, it's definitely possible that large bull (grey) seals have been attacking female common seals and grey seal pups - not just attacking, but eating them or killing them in a way that causes injuries like those seen on the carcasses. This behaviour has actually been observed now.
This is happening on North Sea coasts in the UK and Germany.
Not linked to food availability - there's plenty. No-one's quite sure why some of them have turned cannibal and all aggressive.
But my highly scientific theory is that they are vampire seals, and require seal blood and blubber to survive. The offshore industry has disturbed an ancient power and the seals have been infected with a curse. And it's spreading...