Marine rescue experts yesterday saved a dolphin which had been trapped in a marina for almost a month.

Animal medics lifted the two-metre-long bottlenose dolphin from Maryport harbour, Cumbria, before it was released back into the sea almost a mile from shore.

The rescue followed the unsuccessful attempt to save a bottle-nosed whale from the Thames on January 21.

The 19.2ft mammal died during rescue efforts from dehydration, muscle damage and kidney failure.

Medics from the British Divers Marine Life Rescue (BDMLR) group, which masterminded both rescue missions, said they were delighted with yesterday's rescue.

The animal, nicknamed Marra, had begun to suffer health problems because of the cold and being forced to live in predominantly freshwater. Scientists monitored its condition and spotted pale spots and skin bleaching caused by the lack of salt water.

Tony Woodley, national spokesman for the BDMLR, said: "It was a fantastic rescue and everything went just like clockwork.

"The decision was made to leave the lock gates open as the tide went out so the water level in the harbour decreased. A rescue team went into the water when it was around one metre deep and formed a semi-circle around the dolphin.

"It was captured and put onto a waiting stretcher and then lifted onto the harbour by a crane.

"We then loaded it on to a trailer and took it to a waiting boat where it was taken around a mile out to sea and released. The whole operation took about 20 minutes.

"It was seen to dive and surface around four or five times and then, just like a Hollywood ending, it was seen to meet up with another dolphin and they swam away together. A really happy ending."