Experts initially thought that ship propellers might be to blame for the Grey Seals’ injuries. However, experts now believe the corkscrews are likely due to cannibalism – males attacking juveniles. The Sea Mammal Research Unit, part of UK’s Natural Environment Research Council Collaborative Centre, suggests that cannibalism is more likely. According to SMRU, there’s strong evidence that spiral seal deaths are caused by predatory behaviour of grey seals rather than ship propellers. Researchers saw a male grey seal killing five pups and leaving behind the signature corkscrew injuries. Similar events in Germany could indicate that such predatory behaviour is not uncommon and may explain recent incidents of injured seals along the Scottish coast. A grey seal litter of two pups was partially killed by an adult grey seal. The researchers think that ship propellers are now less likely to be a factor in the deaths of grey seal pups. Richard Lochhead, Scottish Environment Secretary said that the clusters of deaths caused by corkscrew seals was unusual and concerning. Seals share a common trait with other sea creatures. They are beloved by many people. “We now know that ship propeller injury is not the cause of these unusual deaths. We need to understand why they occurred. This information provides some comfort to the shipping industry.” “This will inform regulators and developers, allowing them to consider it in their operations. Marine Scotland will monitor the seal population to see if there are any further injuries or evidence. They were not explained by experts. Marine Scotland asked the St. Andrews University SMRU to investigate the cause of the injuries. The investigation pointed to certain types of propellers being the culprits up until the end of 2014,. This was confirmed by scale models. The photos show an adult grey seal lifting and carrying a young pup to freshwater. This causes the spiral laceration or “corkscrew cut” and is shown in this series. (Photo by SMRU). The SMRU funded the tag of some grey seals living in the Firth-of-Forth. This allowed them to see how they interact with ships and, if necessary, to determine if any were injured. Investigators observed an adult male grey seal attacking grey seal youths. Surprisingly, they were able to observe and record that these injuries had been caused by adult grey seal predation. The researchers reported that 2014, an older male grey seal approached a grey seal pup on the 2nd of December. The adult grabbed the puppy by its neck and carried it to the shallow pool. The adult then grabbed the pup by the scruff of its neck, and submerged it under water until the struggle ended. The skin was then ripped along an approximate. 20 cm. 20 cm. Citation: “Preliminary Report on Predation by Adult Grey Seals on Grey Seal Pups as a Possible explanation for Corckscrew Injury Patterns seen in Unexplained Seal Deaths,” Dave Thompson and Joe Onoufriou. Sea Mammal Research Unit Report for the Scottish Government.
