The oceans would be cleaner Corals would get some respite
Recent years have seen single-use plastics demonised as the public has woken up to the effects of marine plastics. But few people realise the contribution that fishing makes. Lost fishing gear accounts for about 10 per cent of all marine litter and, according to a 2018 study, 86 per cent of the big pieces of plastic floating in the ‘Great Pacific Garbage Patch’. Without fishing, we’d also wipe out pollution and emissions from fishing boats (one 2014 study claimed that lobsters were the most fuel-intensive species, with some boats using 20,000 litres of fuel to catch a single tonne). However, aquaculture could bring other sources of pollution, such as feed and chemical products that are used to control disease. These pollutants enter the sea where fish are farmed in pens and cages. Franco says that aquaculture is, at least in some sectors, less polluting than it was. “Consider salmon farming in the UK – antibiotics have not been routinely used in years,” she says. “But regulations and conditions can be very different in different sectors and countries.” Nevertheless, aquaculture globally will have to become more sustainable if the farmers want to access the most valuable markets, as these demand higher standards.
A further concern is that pushing seafood production onshore into high-tech systems like recirculating tanks would take space from other food production industries. One space-saving solution could be an integrated, ‘multitrophic’ system, growing fish, bivalves like mussels, and seaweed altogether. Gentry reckons that anything involving seaweed is “fabulous”, as the plants extract pollutants from the water, helping to purify it.
Fishing affects the whole ecosystem and, as such, reef fishing has had a huge impact on some of the most vulnerable marine ecosystems – corals. Banning fishing could not only relieve pressure on some of the 4,000 fish species that live around coral reefs, but also on the corals themselves.
It’s not always immediately obvious how fishing affects the corals, but Purcell gives one example. Crown-ofthorns starfish are a scourge on reefs because they eat the living part of the corals – the polyps. If the starfish populations are not controlled by predators, too many polyps will fall prey to these spiky creatures. But the starfish’s predators are emperor fish, which are caught for food, and triton snails, which are prized for their shells. “I don’t think [fishing] is the only reason we’re getting outbreaks of crown-of-thorns starfish,” says Purcell. “But it’s one of the problems, and it contributes to taking out the [starfish’s] predators.”
Meanwhile, climate change and increasing sea temperatures continue to stress and bleach corals, which can then become overgrown with algae. A fishing ban could help bolster populations of the fish needed to clean away this suffocating slime. Cleaning up coral reefs could also ensure that they remain tourism destinations for years to come, supplying local communities with precious income, especially if fishing wasn’t an option.