Proof basking sharks are all go
IRISH scientists have recorded the world’s second largest fish making the transatlantic journey from Ireland to America for the first time ever.
The giant basking shark – which can reach lengths of 33ft – can be spotted in their thousands along the west and north coasts of Ireland in the warmer months, feeding on plankton.
But their whereabouts was a mystery outside the summer season and it was speculated that they would dive deep into the ocean for long periods as they don’t have to surface to breathe.
Now, a new study from Queen’s University Belfast has revealed that a basking shark tagged in Malin Head was discovered swimming off Cape Cod, which is the first ever record of a transatlantic journey between the two countries by the enormous fish.
The study is the first evidence that the world’s second largest living shark do indeed swim between well-known American and European coastal basking shark playgrounds.
‘It’s been a long time coming and this is the first confirmation of that link,’ said the study’s lead author, Emmett Johnston.
‘Our finding identified the link between these surface spots on both sides of the Atlantic.’
He said their research partners in Massachusetts Institute of Technology are ‘very excited’ after years of tagging the sharks on opposite sides of the coast.
The female basking shark – Cetorhinus maximus – was tagged with a satellite transmitter at Malin Head in August 2014 before heading to Scotland a few days later.
The signal went silent after that, but she was re-sighted with a group of other sharks unexpectedly 993 days later at Nauset Beach, Cape Cod in the US – a distance of 4,632km by an underwater diver.
At this stage, the batteries in the tag worn by the shark from Malin Head had worn out but the underwater cameraman zoomed in on the details of the tag which was traced back to Ireland.
‘This has linked three of those spots, the north coast of Ireland with the west coast of Scotland in a single season and a few years later that same shark turns up off the coast of America,’ said the marine biologist.
‘It puts an onus on Ireland, the UK and the US.
‘We have a species that undertakes great Atlantic-wide movement so we need to work together to ensure they are conserved.
‘With protection, there would be by-catch [protection] and ship strike would be a big thing because they swim very slowly,’ said Mr Johnston.
The study, which has just been published in the Journal of Fish Biology, noted there had been only one previous record of shark crossing the Irish Sea to Canada, despite the tagging of over 1,600 sharks.