Rare ‘shark nursery’ discovered hidden in deep waters west of Ireland

Damaged coral reef being used by predatory fish as surface to lay eggs in vast numbers

An enormous shark ”nursery” swarming with the predatory fish and strewn with their eggs has been found in the waters 200 miles off the western Irish coast.

The rare discovery was made by a remotely operated vehicle exploring the region’s cold-water coral reefs at depths of around 750m.

Scientists observed a large school of blackmouth catsharks, a relatively small species found throughout the northeast Atlantic, alongside the more unusual and solitary sailfin roughshark.

The site’s egg cases, or mermaids purses, are seldom seen in such vast numbers, and are thought to belong to the catsharks.

While there were no shark pups swimming around the site, the researchers behind the SeaRover survey that captured the footage want to keep an eye on events there and potentially watch them hatch in the future.

“No pups were obvious at the site and it is believed that the adult sharks might be utilising degraded coral reef and exposed carbonate rock on which to lay their eggs,” said David O’Sullivan, chief scientist at SeaRover.

“A healthy coral reef in the vicinity, may act as a refuge for the juvenile shark pups once they hatch.

“It is anticipated that further study of the site will answer some important scientific questions on the biology and ecology of deep water sharks in Irish waters.”

The new findings were announced at INFOMAR Seabed Mapping Seminar in Kinsale this week, where the marine scientists played highlights taken by the Holland 1 underwater vehicle.

“We are delighted that this discovery has been unveiled at todays’ event, demonstrating the importance of mapping our seabed habitats in understanding and managing our vast and valued ocean resources,” said Mr O’Sullivan.

“Our data and team continue to make significant contributions to harnessing our ocean wealth.”

Informar is an Irish government initiative, and the new discovery will help the country meet its obligations to monitor deep water sharks as part of its marine conservation programme.

The nursery was found within one of six special areas of conservation in Ireland’s enormous ocean territory.

These regions, designated by the EU, are home to an enormous variety of creatures from sea fans to a variety of fish species. Due to their protected status, fishing trawlers are not allowed to operate in these zones.

“Our key objective is to assess, protect and monitor Ireland’s rich offshore marine biodiversity so we can begin to manage our marine resources effectively,” said Dr Yvonne Leahy from the Irish National Parks and Wildlife Service.

“Without knowledge of what lives in our seas we are at risk of never fully understanding and appreciating Ireland’s marine environment.”