Shy Risso's dolphins found off Bardsey Island, Gwynedd

The large grey Risso's dolphin has a blunt nose and can remain submerged for half an hour

A rarely seen species of dolphin has made its home off the coast of Gwynedd, according to a conservation group.

The Risso's dolphin, which can dive to around 1,000ft (300m), has been returning regularly to live and breed in the waters off Bardsey Island.

Whale and Dolphin Conservation (WDC) said more than 100 of the shy mammals make their home there in the late summer months.

It says conservation initiatives must take the species into account.

WDC carried out what it calls "patient" research, part-funded by Natural Resources Wales, into Risso's dolphins in the region for almost two decades.

Its study, published in the latest edition of the Open Journal of Marine Science provides the first population estimate for the Risso.

The species tends to avoid boats and its ability to dive to such depths gives it an air of mystery, according to the conservation group.

Researchers have slowly built up a collection of ID images of individual dolphins so that they can be recognised and tracked over time.

The researchers say that the fast-moving waters around Bardsey may be part of a network of localities important to the species, where it can take advantage of prey in shallow waters.

They also say there is a variety of conservation initiatives in Cardigan Bay and the north Wales area, particularly over the designation of marine protected areas.

However, none specifically take the Risso's dolphins into account.

"Our study shows the {Cardigan} Bay to be important for the elusive and little known Risso's dolphin, which should provide additional incentive for regional conservation strategies," they add.

Chris Butler Stroud, WDC's chief executive, said: "This new research underlines that this is a small population and that the waters of north Wales are important for it.

"We must do everything in our power now to make sure this small group survives."

Cliff Benson, director of the Sea Trust, said the numbers of Risso's dolphins in the sea off Wales in general appear to be on the upward trend.

"There are two definite hot spots, one approaching the Tusker Rock just off Rosslare the 'Risso's Triangle' and another lesser hotspot near the Welsh coast," Mr Benson said.

"Historically, we have regularly seen Risso's dolphins from Strumble Head near Fishguard over the past 30 years.

"In fact, next to the resident porpoises they are probably the cetacean most often seen from there.

"We also have seen them pretty consistently near the Pembrokeshire islands - Skomer, Skokholm, Grassholm and the Smalls - in the past couple of years."