A COUPLE on a fishing trip kept watch over a baby harbour porpoise for two hours while it lay in Portland Harbour waters.

Professional divers Izzy Imset and Nina Hukkanen feared the mammal was dead or injured when they spotted it floating on the surface as they returned to the harbour in their boat Ahti.

They soon realised the creature - which they named Pebbles after their dog - was alive, so stayed nearby and warned passing vessels to steer clear of it.

Izzy, from Portland, said: "We spotted something lying flat on the surface close to the moored yachts at Sandsfoot Castle. It didn't move even though we were close, so we killed the engine immediately.

"At first I thought it was a dead dolphin, but we approached slowly and saw it breathe once and realised it was alive. Then we saw it was a small porpoise that had most likely been separated from its group.

"It was less than a metre long and looked like a piece of cardboard with a fin sticking out. As we were worried about fast boat traffic we stayed with the porpoise in a large circle with the engine on slowest speed."

The pair alerted Portland Coastguard who contacted the British Divers Marine Life Rescue (BDMLR) and a team of trained medics was put on call.

While Izzy and Nina were warning the skipper of a Weymouth dive boat to keep away from Pebbles, the porpoise suddenly swam away. Now the pair want boat crews to make sure they avoid Pebbles who may still be in the waters around Weymouth and Portland.

Martyn Dean, BDMLR southern area co-ordinator, said he believes the porpoise may have been exhausted after battling against strong waves or could have been simply basking in the sun.

He added: "Its breathing rate was only slightly slow, which suggests it wasn't in distress or about to die. This couple did exactly as they should by calling the Coastguard and observing from nearby. Nobody should get in the water or touch a mammal like this."

Mr Dean estimates there are between 50 and 60 porpoises living off the Dorset coast and says there are only six or seven sightings of the mammals a year in the South West.

Anyone who suspects a mammal is in trouble should contact the Coastguard or phone the BDMLR on 01825 765546.