A team of Irish marine scientists has discovered a very rare "shark nursery" 200 miles of the west coast.
The announcement was made at the INFOMAR Seabed Mapping Seminar in Kinsale today, where video highlights were debuted of this rare occurrence.
The nursery was discovered during the recent “SeaRover” survey in July by the Marine Institute’s remotely operated vehicle (ROV) Holland 1 deployed onboard the ILV Granuaile.
Very large numbers of egg cases, commonly called mermaids purses, were filmed on the seafloor at depths reaching 750m. Such large concentrations of egg cases, are rarely recorded and indicate females may gather in this particular area on the seafloor to lay their eggs.
A large school of Blackmouth catshark (Galeus melastomus), abundant in the northeast Atlantic were present at the site, and it is likely the eggs are of this species. A second more unusual and solitary species, the Sailfin roughshark (Oxynotus paradoxus) was also observed.
Both species are of scientific interest as Ireland has an obligation to monitor deepwater sharks under the Marine Strategy Framework Directive.
The Sailfin roughshark 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 1.2 m and is usually observed moving slowly with deep water currents feeding on small benthic invertebrates. The individual may have been feeding on the eggs although this was not observed by the science team.
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.
Speaking at the event David O’Sullivan, of INFOMAR and chief scientist on the SeaRover survey (Sensitive Ecosystem Analysis and ROV Exploration of Reef habitat) said the nursery was of 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," he said.