You might think – with its feeding frenzies, vertiginous seamounts, perilous weather and deep history of the monstrous – that the ocean was a wild enough place as it is; but according to the environmentalist Charles Clover it has systematically been ‘de-wilded’ by decades of commercial overfishing, and our seas are now in urgent need of healing. I believe him.

When it comes to conservation, fish hold less appeal than terrestrial fauna: they are perceived as cold-blooded, mostly invisible, lacking in charisma, and often delicious – plus, for centuries, there existed the comfortable delusion that their stocks were inexhaustible (even a proof positive of divine benevolence). Now, thanks to ruinously efficient modern trawling techniques, poorly enforced regulations and sheer greed, this abundance is palpably at an end.

A wider awareness of the crisis, and the attempt to reverse international trends, was promoted by Clover’s previous book, his influential The End of the Line, and a subsequent documentary film which highlighted in particular the plight of bluefin tuna (a single specimen of which was once sold in Tokyo’s Tsukiji fish market for £2.5 million) and explored the devastation to marine ecosystems caused by this industrial plundering of the seas. Its premiere in 2009 was memorably associated with a photograph of a naked Greta Scacchi hugging a large cod.

In several ways, Rewilding the Sea is a follow-up volume – indeed, it begins with the welcome reappearance of tunny off our own Western Isles – and charts the progress that has been made in the intervening period. Although urgent and sometimes indignant in tone, this is far from some shrill doom-sayer’s polemic. It describes ‘how things once thought impossible have happened,’ largely through the creation of marine reserves across the world, many of the ones the author charts having been championed by the Blue Marine Foundation (BLUE), a charity of which he was co-founder. ‘We have industrialised the sea, and lied about protecting it,’ is this excellent book’s pithy, incontestable premise.

Rewilding has become a fashionable buzzword, but it is not universally popular – try discussing with any of my hill-farming neighbours in Perthshire the prospect of reintroducing wolves, or the already thriving beaver colonies of Tayside (which I’m told would furnish a spectacular sporran). Clover takes its marine application to mean setting aside designated, and properly monitored, areas of the seas where nature can be allowed to take its course and repair damage to depleted habitats; but this approach does not always appeal to officialdom, which prefers analysis of data before taking action – and for that, he argues, we do not now have the luxury of time.

Another major problem is that even where agreements exist, they are feebly enforced. Around our own shores, some 97 per cent of protected areas are still being fished by some method, and it is anyway difficult to establish entirely ‘no-take’ zones. In Lyme Bay, where ‘England’s coral garden’ has been reduced to rubble by scallop-dredging, it took a 23-year campaign before the government imposed a restriction protecting 60 square miles, by which time biodiversity in the area was seriously threatened. In the words of the Dorset lobsterman Dave Sales (to whose memory the book is dedicated): ‘I think we overdone it a bit.’

Whether it be the sturgeon feeding grounds of Dogger Bank, the reseeding of oyster beds in the Solent or the protection of kelp forests off Bognor, conservation projects face the perennial challenge of reconciling their plans with traditional local fishing practices, but not all authorities are imaginative about this. When crofters alerted Marine Scotland to the location of a rare skate nursery off Skye, a no-fishing zone was set up that excluded them from even setting their creels – but that’s another type of Sturgeon problem. The spectre of bureaucracy haunts most of these interlocking case studies, and occasionally frustration proves too great. In 2020, when Greenpeace began dropping granite boulders in the North Sea to obstruct electric pulse trawlers, the author had his name inscribed on one. ‘I believe in the law,’ he writes, but ‘nature has its needs too.’

It is the human factor that makes this book so immediate, and Clover realises that there are only so many acronyms and statistics that the general reader can cope with before an eco story becomes as dry and unappetising as a bagful of Icelandic bitafiskur.

Especially heartening are his accounts of how certain relatively small local populations are confronting the depredations of heavily subsidised long-range industrial fleets, frequently from the ravenous East. The dramatic chapter ‘Jurassic Parks of the Sea’, concerns a project to protect the waters surrounding some of Britain’s 14 Overseas Territories, including Ascension Island (which I recall being the only place you could get a drink on the long, dry flight to the Falklands) and its remote sisters St Helena and Tristan da Cunha. Although islanders derived vital income from the selling of commercial licences, it was shown that the disastrously unsupervised industry, which involved trawlers as well as long-liners that finned live sharks, was damaging the whole biological web that also supported green turtles, land crabs, frigate birds and specimen wahoo. Eventually, the residents were persuaded to accept a UK government conservation scheme – helped this time by an image of Helena Bonham Carter embracing a yellowfin tuna. The total areas now protected extend to 1.5 million square miles.

In the Indian Ocean, another extensive reserve has been established around the Chagos archipelago, from which the British notoriously deported the entire population in 1973 as part of a military deal with the USA. It is home to 220 species of coral and 800 species of fish, but Mauritius is laying claim to it, and that’s a country with a truly dismal record of marine stewardship. However, further to the north, in the Maldives, there are signs that an enlightened government is aware of how tourist developments and pollution are threatening their precious reefs: a previous president even held a cabinet meeting underwater to flag up the dangers of rising sea levels.

The vast long-range fishing fleets of China and the EU are among Clover’s ‘Enemies of Progress’, as they shamelessly exceed their catch limits, especially around the African coasts. Trawlers release as much CO2 as the global aviation industry, and their detrimental impact on the ability of the seabed and its denizens to soak up carbon is one of the book’s abiding themes. But Clover insists that rewilding is catching on, and its benefits are discernible. This is an important, intriguing and informative book, and I would like to share his admirable optimism. As the philosopher Francis Bacon remarked: ‘Hope is a good breakfast, but it is a bad supper.’