A rare ‘shark nursery’ has been discovered by a team of marine scientists 200 miles (320km) off the western coast of Ireland.

The Marine Institute’s remotely operated vehicle Sea Rover was investigating Ireland’s deep cold-water coral reefs at depths of around 2,460ft (750m).

Scientists recorded a large school of catshark pups, usually found in the north east Atlantic, along with the more unusual solitary sailfin roughshark.

Sea Rover’s operators spotted thousands of egg cases, commonly referred to as mermaid’s purses, strewn along the ocean floor.

The scientists discovered a large school of catshark pups, usually found in the north-east Atlantic. This is a rarely observed habitat within an offshore Special Area of Conservation

Experts believe the ‘mermaid purses’ were deposited by the females during the summer months, which may mean that they regularly come to the area to lay their eggs.

Coral skeletons – a reef made of thin layers of calcium carbonate – found in the region make ideal environments for marine wildlife to lay and deposit their eggs.

Other sea creatures are seen in the footage co-existing with the sharks – including sea urchins, crabs and other smaller fish.

The scientists recorded a large school of catshark pups, usually found in the north east Atlantic, along with the more unusual solitary sailfin roughshark

The solitary sailfin roughshark is on the ‘Near Threatened’ by the International Union for Conservation of Nature meaning it may be considered threatened with extinction in the near future

The rare Sailfin roughshark is seen on the periphery of the ‘nursery’ area and is thought to be moving through the site potentially to forage on the egg cases, although this was not observed by the science team.

The species is listed as ‘Near Threatened’ by the International Union for Conservation of Nature meaning it may be considered threatened with extinction in the near future.

The species grows up to a length of four feet (1.2m) and is usually observed moving slowly with deep water currents feeding on small benthic invertebrates.

The findings were announced at INFORMAR Seabed Mapping Seminar in Kinsale, where the marine scientists played highlights taken by the underwater vehicle.

The Marine Institute’s remotely operated vehicle Sea Rover was investigating Ireland’s deep cold-water coral reefs at depths of around 2,460ft (750m)

Scientists believe the egg cases or ‘mermaid purses’ were deposited by the females during the summer months, may mean that they regularly come to the area to lay their eggs

INFORMAR is an Irish Gorvernment Initiative which monitors  deep water sharks as part of its marine conservation programme.

David O’Sullivan, of INFORMAR said:  ‘We are delighted to report the discovery of a rare shark nursery on a scale not previously documented in Irish waters.

‘This discovery shows the significance of documenting sensitive marine habitats, and will give us a better understanding of the biology of these beautiful animals and their ecosystem function in Ireland’s Biologically Sensitive Area.’

While there were no shark pups swimming around the site, the researchers 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.’