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Global Ideas

Ghost nets threaten marine wildlife

Once lost or discarded, old fishing nets can drift through the world’s seas for centuries, catching and killing marine wildlife as they go. Environmentalists and local groups are working to combat the threat.

When he saw a sea turtle with both its front flippers torn off, Martin Stelfox knew he had to do something. Working as a marine biologist in the Maldives, he was no stranger to the sight of wildlife injured after becoming entangled in abandoned, or ghost, fishing nets. But in 2013, the sight of this particular olive ridley turtle drove him to set up an eponymous project that highlights and tackles a worldwide problem.

Ghost nets are fishing nets that have either been lost or discarded at sea. Small fish, which are usually the first to become trapped in their mesh, attract larger species and other marine predators including sharks, dolphins, sea turtles and even marine birds.

When the weight of their incidental catch gets too heavy, they sink to the bottom of the seabed, where the dead wildlife decomposes. When that happens, and the net is light enough, it rises back to the surface and everything starts over. It is a perpetual cycle of what is known as ghost fishing.

Even those that sink to the ocean floor empty, cause damage to vegetation, wildlife and reefs.

A codfish trapped in a ghost net.

A codfish has gotten trapped in a ghost net stuck on a shipwreck in the Baltic Sea. Photo: Wolf Wichmann/archaeomare/dpa

Often made from synthetics, the nets can drift in the ocean for decades, trapping and killing as they go. “Essentially, they are made for eternity,” Dr. Kim Detloff, Head of Marine Conservation for the Nature And Biodiversity Conservation Union (NABU), told Global Ideas. “They can last in the ocean for up to 600 years.”

Worldwide problem

Ghost nets are a global phenomenon, but ocean currents sometimes mean the damage is done far from where the nets are lost or abandoned. The Maldives, for example, have banned any kind of net fishing within their territorial waters, yet Martin Stelfox’s Olive Ridley Project recorded 107 ghost nets on the Maldives during its first year of operation. 54 of them had trapped one or more sea turtles.

The project invites the diving and fishing communities to pass on any information about nets they might find floating in the Indian Ocean. In working together and broadening awareness of the issue, they hope to reduce damage caused.

Some technological advances are also having a beneficial effect. Although from a conservationist point of view, large-scale commercial fishing is regarded as damaging, Detloff says the high-tech nature of the industry has led to a fall in the number of vast commercial nets lost in shallow waters.

“Thanks to GPS and detailed maps of the ocean floor, the fishermen can steer clear of obstacles the nets might snag on,” Detloff said. “And these nets aren’t cheap, so the fishermen have a strong incentive to preserve them.”

In the North Sea, however, it is harder to avoid obstacles at great depths, which makes deep sea nets problematic. But even the smaller ones used by local fishermen the world over can, and do, kill and maim marine wildlife. Thilo Maack, Oceans & Biodiversity Campaigner at Greenpeace Germany, says the solution lies in legislation.

“Net disposal has to be free of charge," he said, adding that commercial nets should be equipped with tracking transmitters so they can be found if lost.

Retrieving the Nets

In many parts of the world, efforts are being made to collect ghost nets and other plastic garbage from the sea. Working with fishing boat crews and professional divers, WWF Germany has launched a campaign to collect abandoned nets from wrecks and the ocean floor in the Baltic Sea.

“We have groups working in Germany, Poland and Sweden," Dr. Philipp Kanstinger, Program Officer Seafood Certifications at WWF Germany said. "But we are aiming to become active in other seas as well.”

Young seagull killed in a ghost net.

Young seagull killed in a ghost net. Photo: NABU/J. Baer

Another group working to remove the hazards from our seas is Ghostfishing - a volunteer group of technical divers. Based in the Netherlands, they have inspired other divers around the world to use their expertise to collect stray fishing gear.

Finding a new use for ghost nets

GhostNets Australia, which started out as an alliance of 15 indigenous communities living along the country's northern shores, takes a land-based approach. Rangers there have collected more than 13,000 nets that have washed up on the 3000 km of shoreline they patrol.

But collecting the nets is only a first step. How can the mountains of old mesh be reused? Groups like Ghostfishing send them to nylon manufacturer, Aquafil, to be recycled into new fibers that are used in the production of synthetic carpeting and textiles.

GhostNets Australia takes a more creative approach to reusing the nets that wash up on their shores. They take them to their communities where people apply traditional weaving skills to turn them into bags, baskets and mats. Today, many of the nets are even reborn as striking pieces of aboriginal art.

Grey seal entangled in a polypropylene fishing net on the North Sea coast.

Grey seal entangled in a polypropylene fishing net on the North Sea coast.