A basking shark tagged in July with a satellite transmitter off Malin Head, Co Donegal has just released its transmitter west of the Cape Verde Islands, over 5000km away from were it was originally tagged.
The Irish Basking Shark Study Group describes the movement by the five-meter-long female shark 'Banba' into warm tropical waters off West Africa as "highly unusual".
Previous basking shark tracking studies undertaken in the north east Atlantic have only recorded shark movements within temperate waters.
The group says "the recording of this magnificent journey by a basking shark from Malin Head to warmer tropical waters questions many of the fundamental theories marine biologists have regarding the species and its life-cycle".
Malin Head on the Inishowen peninsula where the shark was originally tagged and named by pupils at Scoil Naomh Mhuire has recently been recognised as one of the world's top summer hotspots for the basking shark.