Tuesday 13 November 2018

Scientists discover 'very rare' shark nursery off west coast of Ireland

SeaRover (Sensitive Ecosystem Assessment and ROV Exploration of Reef) SeaRover Survey Team image.
SeaRover (Sensitive Ecosystem Assessment and ROV Exploration of Reef) SeaRover Survey Team image.
SeaRover (Sensitive Ecosystem Assessment and ROV Exploration of Reef) SeaRover Survey Team image.
Paul Melia

Paul Melia

MARINE scientists have discovered a “very rare” shark nursery, 320km off the west coast.

The nursery was discovered during an investigation of Ireland’s deep ocean territory, and shows the seabed littered with eggs, or so-called “mermaids' purses”. 

Striking images show very large numbers of egg cases filmed on the seafloor at depths of up to 750 metres.

Such large concentrations are rarely recorded and indicate that females may gather in the area to lay their eggs.

Nearby coral reef might also act as a refuge for juvenile shark pups when they hatch.

A large school of Blackmouth catshark (Galeus melastomus) was present at the site, and scientists said the eggs were likely to be from this species.

But 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 deep-water sharks under the Marine Strategy Framework Directive”, said Maurice Clarke from the Fisheries Ecosystem Advisory Services at the Marine Institute.  

The Sailfin roughshark is listed as ‘Near Threatened’ by the International Union for Conservation of Nature, meaning it may become extinct in the near future.

It grows up to 1.2 metres in length, and while not observed by the science team, it may have been feeding on the eggs.

The nursery was discovered during the SeaRover survey undertaken last July, which was exploring Ireland’s deep-water coral reef systems.

The research was funded by the Government and State agencies, and the EU’s European Maritime and Fisheries Fund.

The findings were announced at the INFOMAR Seabed Mapping Seminar in Kinsale today, at which video highlights were showed.

The footage was captured by the Marine Institute’s remotely operated vehicle (ROV) Holland 1, deployed onboard the ILV Granuaile.

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: “We are delighted to report the discovery of a rare shark nursery on a scale not previously documented in Irish waters.

“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. 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.”

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