1. Give nature a helping hand by reintroducing species
Some ocean species and habitats struggle to recover on their own and need help. Take sea otters, which were virtually eliminated by the end of the 19th century by commercial hunting for their super-dense pelts.
From the 1960s to 1990, some sea otters were moved to repopulate places where they had once lived. Today there are about 150,000 sea otters in the wild and a third of them are descended from translocated otters.
The US Fish and Wildlife Service is now considering moving more otters to fill in the gaps, including along the coast north of San Francisco. The motivation for this is partly because otters can help keep entire ecosystems healthy.
Without otters to keep their numbers down, sea urchin populations explode and kelp forests become grazed down to the seabed. When otters returned to Alaska and British Columbia, so did the kelp forests.
Efforts are also under way to save the otters’ fellow predators. Sunflower sea stars are colourful starfish the size of bicycle wheels and also have a big appetite for sea urchins. But in 2013, a devastating disease struck the sunflower sea stars, turning them into piles of goo, and their populations collapsed.
A few of the remaining healthy sunflower sea stars were moved into laboratories at the University of Washington, where researchers worked out how to breed them in aquariums. If the sea stars do not recover by themselves in the wild, there is now at least a possibility of reintroducing the species from captivity.
2. Turn off the tap of pollutants
To save the oceans, humanity needs to stem the flow of pollutants pouring into it. More people than ever care about the menace of pollution in our waterways and seas, from Britain’s sewage-tainted rivers to the plastic bags snarling up the guts of whales.
A groundswell is building towards the change that’s needed, with negotiations over a global treaty on plastics continuing at the United Nations. Those who want to limit the manufacture of plastic are battling those who claim we can recycle our way out of trouble, though global recycling rates have stalled at about 10%.
The problem of “forever chemicals” is also more widely recognised. These pollutants are used in all sorts of everyday goods, including furniture, food containers, non-stick cookware and school uniforms.
Virtually indestructible, traces of these incredibly dangerous chemicals linger in wildlife, water and human bodies. Tiny amounts increase cancer risks and are linked to a long list of serious health problems, from liver damage to birth defects, while adding to the stresses on seals, sea lions, dolphins and whales.
So far, few forever chemicals have been banned, and only after long legal battles. Now, calls are growing for a blanket ban, in part to stop the chemical industry from pulling its old trick of replacing one damaging substance for another.
3. Curtail big fisheries
An obvious way to save many ocean species is to stop catching and killing so many of them.
By the mid-20th century, commercial whalers had killed more than 99% of blue whales’ Antarctic subspecies. The biggest animals known to exist were absent for decades even after the global ban on industrial whaling, but in recent years scientists have spotted them again around South Georgia island. Their songs, recorded on hydrophones across the Southern Ocean, herald the whales’ return.
Species can also recover while they are still being hunted. Fishing regulations, if well drafted and properly enforced, can protect populations from overexploitation and revive depleted species. After disappearing for decades, bluefin tuna are returning to British seas after catch limits in the Atlantic were reduced.
In the Cayman Islands, fishing for Nassau groupers is now strictly controlled. It is illegal to catch or sell the half-metre long fish during the winter spawning months. The rest of the year there is a daily catch limit of five fish per boat. Gradually, the groupers are visiting spawning sites in greater numbers.
More fisheries need to be effectively managed and their damage limited, in particular industrial fishing.
4. Keep areas of the sea out of bounds
A tried-and-tested method for boosting sea life is to leave parts of the oceans completely alone, with no fishing or extraction at all. A shocking number of marine protected areas (MPAs) are still being fished, often legally and using highly destructive methods. In 2023, industrial bottom trawlers spent 196 weeks dragging heavy nets along the seabed inside British MPAs.
A tiny portion of the global ocean is under strict protection but these reserves are reaping phenomenal benefits. One of the largest is the Papahānaumokuākea marine national monument, which covers more than 1.5m sq km (580,000 sq miles) of the Pacific Ocean around the north-west Hawaiian islands. Studies have shown schools of tuna that migrate through the surrounding seas have been increasing, probably because their spawning grounds are now protected.
Much of the ocean needs similar protection, such as the thousands of deep seamounts festooned in rich forests of coral and sponges. Existing marine parks need to be better protected and regulations need tightening so they have a meaningful impact on ocean life. Protecting coastal areas is best done in close consultation with local communities; careful planning ensures both nature and people benefit.
5. Ban deep-sea mining
The future of the ocean partially depends on whether a destructive new industry is allowed to start exploiting the deep seabed for rare minerals.
Rich mixes of life on the deep seafloor – from “Barbie piglet” sea cucumbers to ghostly white octopuses – occur nowhere else and play vital roles in oceanic health that scientists are only just beginning to fathom. All that could be at risk if mining goes ahead.
Miners would operate machines like house-sized combine harvesters to scrape and suck up seabed rocks from plains miles below the surface and across vast areas of seabed each year, nonstop, for decades to come. Early targets will probably include a region of the central Pacific roughly the size of the United States.
The big unknown is not whether deep-sea mining could affect the ocean, but just how bad those effects would be. At least a decade of coordinated, well-funded research is needed to answer that question properly. But mining companies, backed by governments, want to begin within the next year.
This year is critical for the future of deep-sea mining. Negotiations continue at the International Seabed Authority – the industry’s gatekeepers – including the first official discussions of a proposed 10-year moratorium.
What the Wild Sea Can Be: The future of the world’s ocean is published by GrovePress –Atlantic Books on 6 June