Thousands of images collected by researchers reveal many of Australia's dolphins are lashed with serious scarring.
While some abrasions are from fights between dolphins and others are likely from boat strikes, others appear to have been caused by sharp teeth.
That's because dolphins are surviving attacks from bull, tiger and white sharks in coastal waters across south, central and north Queensland. Until now, little was known about the predation risk two dolphin species face from sharks or how often they survive these battles.
Researchers from Flinders University discovered high numbers of dolphins observed had evidence of bite marks, including:
33 per cent of the 56 snubfin dolphins
24 per cent of 36 humpback dolphins
Dolphins surviving shark bites that could kill humans
Looking over some of the more extreme images, Caitlin Nicholls from the university’s Cetacean Ecology, Behaviour and Evolution Lab described some of the bite marks as “pretty gnarly”.
“They’re semi-circle bite marks and you can see the punctures from their teeth. There’s often dragging from where the dolphin has wriggled away,” she told Yahoo News Australia.
While these bites would have been enough to kill a person, dolphins have fast-growing, thick skin, allowing them to recover after attacks.
Where are sharks more likely to attack dolphins?
The ongoing study will help researchers understand where dolphins are frequently being attacked and what sort of injuries they are surviving. The data will also provide a baseline, allowing scientists to understand if predation pressure increases.
The closer the dolphins were to the coast, the more likely they were to be scarred. Animals living in Townsville were more likely to have been bitten than those in Gladstone or Bowen.
When researchers had images of the whole dolphin they were more likely to find evidence of scarring. A large proportion of the bites were on the mid-flank, just below the dorsal fin.
“If they get bitten in this area, we think they're more likely to survive the attack,” Ms Nicholls said. “Whereas if they get bitten, maybe on their head or tail, it’s more likely to be a fatal attack because it would immobilise the dolphin and they wouldn’t be able to swim away.”
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