Lord Byron celebrated the sea for being unmarked by the ships that crossed it, unlike the ravages that man inflicted on the land. Even in his day there was trouble brewing out of sight, beneath the surface. Today human impacts on the sea are at crisis point.
Callum Roberts, a professor of marine conservation at the University of York, understands the ocean not just of today, but through time. By mining archaeological sites and ancient literature for data he has helped transform our sense of what the sea was like in humanity’s earliest days. His first book, The Unnatural History of the Sea, took a lyrical and often eye-popping look at how fishing has changed the blue planet.
In Ocean of Life he widens his perspective to map the multitude of Man’s impact on the sea. He charts a course through places where the ocean is being transformed not just by fishing but by warming, acidification, invasive species, pollution and noise, and peers into what the future may hold. Anecdotes and insights lighten the journey, but it is only towards the end that optimism begins to shine.
The Firth of Clyde, off western Scotland, offers a grim glimpse of what lies ahead if politicians continue to bow to the demands of fishermen using nets and dredges that drag along the seabed. Bottom-trawling gear dragged by a single boat can stir up 2,000 tonnes of sediment an hour, leaving “contrails” of mud that can be seen from space. Anything in their paths that can’t escape — the corals, sponges, seafans and seaweeds — face destruction. Worldwide 15 million sq km are hit every year, equivalent to 1.5 times the area of the US or Europe Ocevery day.
In the Firth of Clyde this has resulted in an environment barren of any life other than scallops and prawns. The oysters, horse mussels and clams that used to carpet the seabed are gone. This is not just a necessary sacrifice to food production: today the UK bottom-trawl fleet lands half as much fish as when records began in 1889, despite all the power bestowed by sonic fish-finders, hydraulics and diesel.
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But in one tiny corner of this barren seascape, in Lamlash Bay off the isle of Arran, hope has taken hold. In 2008 a group of islanders managed to bar the trawlers and dredgers and complex habitat is starting to be rebuilt on the silt, creating new “underwater metropolises”.
Roberts explains that a healthy ocean is a necessity for us, not a nicety. Abuse it, and toxic algal blooms give coastal populations streaming eyes, sore throats and breathing difficulties; natural defences against storms and rising tides such as coral reefs, mangroves and salt-marshes have to be replaced by costly sea walls; invasive species clog waterways, affect native species and cause a trillion pounds of damage a year. Wild seafood catches could increase by a third to a half with proper management, but without it could collapse.
A hundred years ago fishermen only worked 1 per cent of the ocean. Today the tables have turned and only about 1 per cent is protected from fishing.
Roberts writes as a scientist as well as a nature lover, passions that coincide when it comes to the stewardship of wild ecosystems. “It is not enough to preserve bits and pieces of nature here and there simply to remind ourselves of what we once had,” he says. Because of his work on what fishermen once pulled from the ocean, Roberts knows the fecundity of which it is capable. For him, conservation is not enough. Our seas need to be restored, not only for nature but for us.
Ocean of Life by Callum Roberts, Allen Lane, 400pp, £25. To buy this book for £21 visit thetimes.co.uk/bookshop or call 0845 2712134