Whales have been caught on camera enjoying a marine version of a day spa, returning to their favourite spot off the Gold Coast to scratch off itchy skin and parasites, and catch up with their cetacean buddies.
Griffith University whale researcher Dr Olaf Meynecke and his colleagues were trying to shed light on the behaviour of competing pods of humpbacks that use Gold Coast waters to rest, breed and socialise.
Over two southerly migration seasons, in late 2021 and 2022, video-equipped sensors stuck to the back of a handful of whales captured five of them rolling around in the sand on the sea floor.
“They were doing these bizarre rolls, going fully on their back and on their side,” the marine ecologist says.
“You could actually see the skin flying off. And then fish would come in and eat it. The fish were also picking skin off the whale, not just the floating skin.”
The whales seemed to seek out roughly the same area – about 10km from Main beach, at a depth of 40-50m.
Meynecke said he would use this year’s southerly migration to look for more evidence of the same behaviour and get samples of the sediment.
He said the area where the behaviour has been observed is likely to have a good mix of sand and fine rubble to help with the shedding process.
“If the skin stays on too long, then barnacles can settle. Obviously, they start very small, and while they are small they’re easy to remove,” Meynecke says.
“But once they become bigger they are very hard to remove for the whale. They can get really quite big, and they are heavy and not good to have around because it impacts their movement.”
The video footage also revealed another secret.
Just like humans, humpbacks appear to think time at the sandy day spa is an excellent way to get quality time with their friends or partners.
“The five individuals were doing this in a very similar context, in a socialising context,” Meynecke said.
“We had two whales that were swimming with each other for several hours. They clearly had a very good relationship and they were both rolling on the ground together and having a great time.”
The phenomenon has been detailed in the journal Marine Science and Engineering.
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