North Atlantic journeys of two blue sharks tracked by UCC scientists

 

THE ODYSSEY undertaken by two female blue sharks from Irish waters around the north Atlantic this winter is being tracked by University College Cork (UCC) scientists, following a successful tagging project off the south coast.

The two sharks were named Granuaile and Queen Méabh by the UCC team during the encounter off Cork’s Old Head of Kinsale a week ago.

While blue sharks have been tagged here before, this marks the first satellite-tracking of the fish with archival “pop-up” tags. Such tags detach after a specific time period, having collected and stored data on temperature, depth and light as the sharks migrate.

UCC scientist Dr Tom Doyle of the university’s Coastal and Marine Resources Centre hopes that the two sharks will “capture the imagination of Irish school children” during their voyage and will also raise awareness about the need for conservation.

Dr Doyle, who is an expert in tracking marine species including leatherback sea turtles and oceanic sunfish, says both sharks face a “real challenge to survive and reproduce in the coming years”, as blue sharks were caught for their fins.

Shark finning is banned by the EU, but there is still a growing demand for fins in Asia.

It is estimated that between five and 15 million blue sharks are caught every year, many as a by-catch of longline fisheries, Dr Doyle says. “Indeed, there is a high probability that one of these sharks will be captured for shark fin soup,” he notes.

Blue sharks are among 28 species of shark prevalent in Irish waters, ranging from dogfish to the basking shark, the second largest fish in the sea.

Blue sharks are regular visitors, arriving each summer during June and leaving in September when water temperature drops below 14 degrees.

Research undertaken by inland fisheries scientists shows such visitors are usually female. They often tend to be carrying young during their time off this 7,800km coastline, having travelled from the east coast of North America and Canada.

A “tag and release” research programme has been undertaken by fisheries board scientists over the past 40 years here, Dr Doyle points out, but this is the first satellite initiative. Sharks tagged by Inland Fisheries Ireland staff have been traced as far away as Barbados, Long Island, the Azores, Canary Islands and the Mediterranean.

This project has been undertaken by Dr Doyle with Luke Harman of UCC’s school of biological, earth and environmental sciences, expert angler and skipper Pio Enright and wildlife photographer Nigel Motyer.

It is expected that some of the initial results will be discussed during a meeting of the Irish Elasmobranch (shark) Group in Galway in November, according to one of its participants, Emmet Jackson.

“Many people are unaware of the great diversity of marine species, particularly shark species, which occur in Irish waters,” Mr Jackson says.