Bottlenose dolphins Tom and Misha were originally captured off the coast of Turkey and used to perform tricks and provide  ‘swim-with’ opportunities for tourists. But in June 2010 the Born Free Foundation animal charity stepped in to rescue them from the tiny concrete tank where they had been languishing in filthy water and were going downhill fast.

They were initially rehomed in a specially constructed sea pen, and over a 20-month rehabilitation period they were transformed back into sleek, efficient marine mammals capable of fending for themselves in the wild.

“The rescue of Tom and Misha has made history,” said Adam M Roberts, chief executive of the Born Free Foundation, which has just published its report on the ‘Back to the Blue’ project. “We now have the hard evidence that it is possible for these animals to be successfully and humanely returned to the wild. That is a very dangerous concept for a multi-million dollar captive industry that profits from their very confinement, posing new ethical and moral challenges for the future of an outdated industry.”

The pioneering project to rescue, rehabilitate and release Tom and Misha was led by marine mammal expert Jeff Foster, who 10 years ago managed the release of Keiko, the killer whale star of the film ‘Free Willy’.

Early analysis suggested that the dolphins retained some of the survival skills they had developed in the wild. But captivity had eroded their fitness, and their reliance on wild behaviour had been replaced by dependence on their trainers.

The rehabilitation team worked to ensure that Tom and Misha were once more capable of maintaining an average swimming speed of 1.5 to 1.7 metres per second – topped with bursts of speed of up to 8.3 metres per second. They were retrained to hunt, kill and consume live fish.

It was important to encourage a truly underwater existence – wild dolphins spend 80 per cent or more of their time below the surface, whereas captive dolphins spend more than 80 per cent of their time at the surface. Another vital factor was encouraging the re-use of echo-location and hearing skills to help Tom and Misha navigate and hunt more efficiently.

The dolphins were eventually released into the Aegean Sea off the Turkish coast in May 2012. It was unclear if they would remain together.Tom rounded the coast at Bodrum and headed north towards Izmir, while Misha headed east along the southern Turkish coast. They were tracked via satellite for several months afterwards, and Tom was subsequently spotted in the summer of 2014.

“In captivity we train the animals not to think on their own, to shut down their brains and do what we ask them to do,” said Jeff Foster. “What we are trying to do when we release them into the wild is get them off autopilot and thinking again. If they can make it alive through a six-month period then we know they have been successfully reintroduced. Within six hours of release they were eating wild fish and swimming with another dolphin. It was fabulous.”

Tom and Misha’s extraordinary journey is documented in a video released to accompany publication of the ‘Back to the Blue’ report. You can watch it on YouTube here: