Forget swiping left or right, basking sharks are good old fashioned ‘speed dating’ through ‘slow love dances’ spotted off the Irish coast.
Over recent years 19 groups of the red-listed species have been spied in mysterious circling formations off Co Clare.
Researchers from the UK’s Marine Biological Association and the Irish Basking Shark Group believe the rare fish were engaged in courtship behaviour.
Read more: 'Shark' spotted off Irish coast as tour boat shares photos of 'huge creature'
And Ireland is the first country in the world where the phenomenon has been verified.
The team of marine biologists caught footage of groups of between six and 23 sharks swimming slowly in circles near the surface and deeper below them in a 3D ring structure they call a ‘torus’.
It was found the groups contained equal numbers of males and females and that they weren’t there to feed.
In a bid to understand the behaviour, researchers took and analysed underwater and aerial footage of 19 groups, at nine locations over six years.
Marine Ecology professor, David Sims, told us: “It’s a natural wonder of the world for sure.”
The Senior Research Fellow at the Marine Biological Association of the UK says while the behaviour has been spotted from above off Canada and the US, no one has ever been able to verify what they were doing.
“These circle formations have never been seen off Ireland or the UK before,” he added.
“Some people have said they are like ‘sharknadoes’.
“It’s speed dating, but in slow motion... but in that timeframe they are interchanging between different individuals.
“Interestingly, some of the big males preferentially checked out some of the big females and vice versa.”
He said one of the big females, F6, “checked out all the big males pretty closely by swimming below them so her fin would touch their claspers, which are the device the male uses to pass the sperm packets to the female when they actually mate”.
“I have been studying basking sharks since 1995 and I have never seen anything like this,” he said.
“It was so slow and mesmeric.. it does look like some sort of love dance. It absolutely fascinating and beautiful to watch.”
Basking sharks are the world’s second biggest shark and can grow as big as 12 metres in length.
But instead of feasting on wildlife like seals and other fish, they use their mouths and large ‘gill rakers’ to catch microscopic zooplankton.
We reported in March how the once heavily fished species is being added to Ireland’s protected animal list following a major campaign that included a petition from children.
Minister of State for Heritage and Electoral Reform, Malcolm Noonan, said at the time: “This move will confer legal protections on them in the short term and enhance their protection in the longer term through the collaborative development of a Code of Conduct to support best practice in sustainable eco tourism.”
If the legislation passes it will be illegal to hunt, injure, interfere with or destroy their breeding or resting places in Irish waters.
Prof Sims added: “They are at risk from shipping strikes... the ones that were studied were at the surface.
He said divers off Donegal “encountered a circle of 30 basking sharks at depth” in October 2020 and that “bottom trawling and set nets might interfere with these circle formations.”
The marine expert also said: “It would be a problem for the sharks if their courtship were to be interrupted by marine traffic and tourism.
“We found the courtship lasts for a long time... they can be there for hours and even days.
“One has to be careful at the numbers of people that might be out there on craft, whether it be jet skis or small boats.”
Find out more about the species here.
