Britain can be proud of its vital role in bringing back the blue whale

It lifts the spirits, given all the things that are happening to our oceans, to hear that blue whales are feeding in the Atlantic waters of South Georgia in numbers unprecedented since hunting was banned in 1967.

These immense creatures grow slowly, have few young and live to be nearly 100, so the population’s recovery from the state that north European whalers reduced it to in the last century – 1 per cent of its size prior to industrial whaling – was never going to happen overnight.

There are still worries that the gene pool may be fatally diminished, that plastics, ship collisions and persistent organic pollutants may cut these glorious creatures’ chances of survival, and that climate change will reduce the plumes of krill on which they feed stretching out from the Antarctic ice. Yet the sighting of 55 whales over a 23-day survey of South Georgia waters – where previous expeditions saw only one or two – must inspire hope in the most despairing of hearts that we can heal our battered blue planet if we try.

Attitudes have changed utterly since whalers from Britain, many of them Shetlanders, flensed their whales at Grytviken on South Georgia. We have realised, too, that whales play a part in the carbon cycle, so their loss has accelerated climate change. Which makes it all the more important that South Georgia and its territorial waters are protected now as part of Britain’s Blue Belt, the ring of protection formed around some of our Overseas Territories, which has been a major policy achievement of successive governments.

South Georgia and the South Sandwich Islands could be even better protected than they currently are from the fishing of krill: Britain continues to license fishing for species on strict quotas there. But what is even more important, according to scientists, is that we give whales and other wildlife more space, so they can survive all the other threats we are throwing at the oceans. For that, scientists say we need to protect at least 30 per cent of the ocean from all extractive activity.

That is a tremendous task, given that we have protected only 7.9 per cent of the ocean so far – against a target the world set itself of 10 per cent by the end of this year. There is hope that Britain may help to close that gap by enabling the protection of the remote waters of Tristan da Cunha, in the south Atlantic, in what many are calling the “super year” for the oceans.

There is little doubt that the Blue Belt is now a global conservation catalyst, and one of which Britain and its territories can feel immensely proud. But if we are to meet that target of protecting 30 per cent of the ocean in the next decade we will have to do more by creating marine reserves in international waters. And post-brexit Britain, as a maritime nation able to speak with its own distinctive voice, will have a major role to play in that.