Off the west coast of Ireland, a deep ocean expedition has discovered a huge shark nursery, something that is very rarely seen.
Infomar, Ireland’s national marine mapping programme delivered by Geological Survey Ireland (GSI), the Marine Institute and the Government, has announced a major natural discovery more than 300km off the country’s west coast.
During a SeaRover survey using the Holland 1 submarine last July, the scientist team discovered a huge shark nursery within Ireland’s deepwater coral reef systems. The significant number of egg cases, often referred to as mermaid purses, were filmed at depths up to 750 metres.
Such large concentrations of egg cases are rarely recorded and indicate that females may gather in this particular area on the seafloor to lay their eggs. Most of the eggs are likely to be from the Blackmouth catshark (common in Atlantic waters) as well the solitary Sailfin roughshark (a more unusual sighting). In fact, the latter 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.
Found in a healthy coral reef
“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. A healthy coral reef in the vicinity may act as a refuge for the juvenile shark pups once they hatch,” said Infomar’s David O’Sullivan, chief scientist of the SeaRover survey.
Keeping an eye on these sharks is not just of scientific interest, the team said, but also of national interest because Ireland has an obligation to monitor deepwater sharks under the European Marine Strategy Framework Directive.
The shark nursery was observed within one of six offshore Special Areas of Conservation (SACs) in Irish waters designated under the EU Habitats Directive for Annex 1 reefs. The SACs host a diverse range of marine animals including sea fans, sponges, worms, starfish, crustaceans and a variety of fish species.