A pod of feeding humpback whales which should still be in the Arctic at this time of year was identified this week off the Waterford coast.
Local fishermen believe there may be five to six of the rare whales off Mine Head.
One was photographed by retired fishing skipper and whale-watcher, Mr Joe Aston, on Wednesday night about 10 miles south of Mine Head, Co Waterford.
Mr Aston, who owns and charters the 45-foot schooner, Anna M, said it was unusual for the humpbacks to be in the area at this time of year.
Humpback whales are best known for the distinctive markings on their tail flukes, and were hunted almost to extinction in the last couple of centuries.
Large numbers were killed when whaling took place off the Mayo coastline. An international photographic identification of most of the surviving whales has been recorded in the Arctic, where the mammals feed.
The whales migrate to breed in the Caribbean, and some have also been found breeding in the Cape Verde islands off west Africa.
Dr Simon Berrow, chairman of the Irish Whale and Dolphin Group, who witnessed this week's sighting with Mr Aston, said that the pod may be bound for Cape Verde.
"However, July is too early for them to be seen here. The last pair we saw - a mother and calf - were identified by Mr Colin Barnes of Castletownshend, Co Cork, last September, and they may have been on their way to west Africa at that stage."
Dr Berrow and Mr Aston, who have already carried out an expedition in the Anna M to the Azores, are seeking sponsorship to mount an expedition to the Cape Verde islands to monitor the whales breeding there and to attempt to match individuals with those recorded in Irish waters.