2023-05-30 11:11:31
Fishing
Ghost nets, invisible scourge of the oceans
Pervasive “death gear” in the oceans, lost or abandoned fishing gear traps marine animals and pollutes beaches around the world. They sometimes end up in museums.
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Whether lost or deliberately abandoned, the net can trap turtles, seals, whales, dolphins and seabirds.
The problem has been known since the 1960s, when fishing fleets began to trade their natural fiber nets for plastic. More efficient and easier to handle, fishing gear (pots, seines, trawls, nets) has also seen their life expectancy at sea increase considerably. Whether lost or deliberately abandoned, the nylon net will therefore remain fishing for months or even years, trapping turtles, seals, whales, dolphins and seabirds.
“These are deadly devices, which have an extremely long lifespan, the most important macro-waste in the ocean”, describes Lamya Essemlali, president of Sea Shepherd France, whose association leads campaigns to recover ghost nets. . In September 2021, the agents of the Iroise marine natural park had thus gone up, off Douarnenez, in Brittany, a ghost net 200 meters long, in which many crustaceans had found themselves trapped.
So many losses for biodiversity and… for fishermen. “Fishermen know very well that a net that is at the bottom continues to fish, so it’s as many potential catches that are lost”, testifies Livier Schweyer, environmental technician at the Marine Park, who adds that the partner fishermen of the park generally report the lost machine and its location.
However, the phenomenon is difficult to quantify. “This is the problem of the marine environment: a lot of data escapes us. Ghost nets are aptly named,” summarizes Livier Schweyer.
Soon a biodegradable net?
The often quoted estimate of 640,000 tonnes of fishing gear lost or abandoned per year is probably exaggerated, according to a study. The fact remains that the problem is omnipresent in all the oceans of the world. A participatory science survey has thus made it possible to identify 27,000 fishing gear or debris on the French coast in just two years, between Brittany and Hauts-de-France.
To limit the damage, researchers are working on biodegradable net projects. In Lorient, still in Brittany, the “Indigo” project has made it possible to develop a prototype net for aquaculture, biodegradable in the marine environment. But its equivalent for coastal fishing has not yet seen the light of day.
“Fishermen know very well that a net that is on the bottom continues to fish, so it’s as many potential catches that are lost.”
Livier Schweyer, environmental technician
“We are not there in terms of resistance,” explains Morgan Deroiné, engineer at the Regional Institute for Advanced Materials (Irma). “Biodegradable plastics don’t have the same properties as nylon, which is very, very strong.”
Not far from there, in Brest, the company Fil&Fab is trying to structure a network for recycling nets with French ports. “We recycle the material in granules and resell it to the plastics industry,” explains Théo Desprez, who estimates the French market at between 800 and 1,000 tonnes per year.
On the other side of the world, it is an artistic movement that emerged following the surge of ghost nets, carried by the sea currents on the coasts of northern Australia. Called “The Art of the Ghostnets”, it is described in a recent book by Géraldine Le Roux, anthropologist at the University of Western Brittany.
Faced with the mass of nets collected, local communities have indeed had to find ways to recycle this mega-waste in island territories, far from major urban centers. By “radically transforming” the nets, “to the point of transforming the material itself”, artists, indigenous or not, have created a wide variety of works, then exhibited at the Biennale of Sydney or at the Oceanographic Museum of Monaco.
(AFP)
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