Up to one million tonnes of fishing gear is left in the ocean each year, creating “deadly” debris for marine mammals, seabirds and sea turtles, conservationists have warned.
The WWF has said “ghost gear” of lost, abandoned or broken nets, lines and ropes makes up at least 10 per cent of marine litter and is the most likely type of plastic debris to prove fatal to marine wildlife.
The wildlife charity warned in a report on the issue that ghost gear was also damaging valuable sea habitats and tourism spots, with the debris continuing to catch fish long after it had been lost.
The organisation has also urged countries to join the Global Ghost Gear Initiative, an alliance of the fishing industry, academics and other groups, focused on addressing the problem worldwide.
“Our ocean is the unsung hero in the fight against the climate crisis. The planet would today already be 35C hotter without the ocean to protect us,” Sarah Young, head of marine policy at WWF, said.
“But the ocean cannot protect us if we do not protect it in turn, and currently nature is in freefall.”
Ms Young added: “By polluting our waters with plastic such as ghost gear, we are destroying wildlife and vital marine habitats that could help us tackle climate change.
“To truly protect both marine life and human life we must put ocean recovery into action, and ensure fishing practices are climate- and nature-positive.”
The report said that somewhere between 500,000 and one million tonnes of fishing gear is left in the ocean each year, with gear being discarded in some instances to conceal illegal fishing activities.
A separate report by Greenpeace Germany found an estimated 640,000 tonnes of ghost gear entered the ocean each year, making up about 10 per cent of plastic waste in the ocean.
The study, published last year, called for stronger international action against plastic pollution, including an agreement to protect at least 30 per cent of the world’s oceans by 2030 from harmful human activities such as industrial fishing.
Marine debris affects two-thirds of marine mammals, such as porpoises, half of seabirds and all species of sea turtles, according to the WWF.
Across all species, abandoned fishing equipment is the most likely to prove lethal - with many creatures dying slow, painful deaths tangled up in old nets or lines, the conservation group added.
“Lost, abandoned or discarded fishing gear can cause tremendous damage to some of our most precious and fragile marine life,” a spokesperson for the Department for Environment, Food and Rural Affairs said in response to the report.
“As an active member of the Global Ghost Gear Initiative, we encourage other nations to join and are working internationally to address the problem of ghost gear.”
To improve the situation, WWF has called for fishing gear to be marked so owners can be identified, improvements for disposal and recycling, and the inclusion of biodegradable components on equipment to help them break down more quickly.
It added that existing programmes, such as “fish for litter” schemes which reward fishers for bringing back marine debris, should be encouraged further.
Additional reporting by PA