I photographed this gannet by the sand martin colony at Redcar yesterday. I did not investigate it closely as I had my young granddaughter with me. Looking at the photo I now see that it appears to be hooked with nylon line?
It's difficult to imagine how this came to happen considering the manner in which they feed, diving in to catch fish. From the line going in the bill it looks as if it picked up a fishing bait, or maybe caught a fish that had eaten the bait? Usually when I see dead birds with fishing line involved it's entangled about their feet or wings.