Photos of the dead seals were sent to the Department of Conservation and were viewed by senior marine science adviser Dr Karen Middlemiss yesterday, who said it appeared parts of the seals had been eaten by an unknown shark species — possibly a great white or sevengill.
"However, due to the appearance of what looks like a straight cut, Doc is investigating whether the body of one seal was tampered with after death.
"It is an offence under the Wildlife Act to kill, remove or keep any part of a protected species."
Dr Middlemiss said seals were a key food source for great white sharks, to sustain their high energy needs — particularly once the shark had grown to about 3m in length.
"Eating the odd snapper or ray is not going to satiate large sharks for long, whereas a small seal will sustain them for several days."
The remains of the seals were found on Allans Beach and photos of them were posted on Facebook recently.
It prompted many people to write posts warning about swimming or surfing in the area, because they might be mistaken by sharks as New Zealand fur seals.
Many believed the decapitations were the work of humans.
"I don’t think sharks are responsible for that," one person said.
"Having worked in Australia’s largest sea lion colony and South Australia’s largest fur seal colonies for years, I can tell you one thing we never saw — a dead seal with shark wounds.
"Saw plenty of living seals with wounds, almost daily, but if a shark gets a seal, it doesn’t leave the head uneaten and it certainly doesn’t leave the entire body uneaten."
Either way, Dr Middlemiss said sharks hunted in areas where seals were present and warned swimmers to be aware of them.
"Great whites and sevengill sharks are common along Dunedin’s coastline.
"There is a higher risk of sharks being present around seal colonies.
"Sharks are also more active at dusk and dawn over summer months," she said.
