Ghost nets – the hidden marine polluters

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Fishing industry cause of most plastic waste in world’s oceans

Plastic packaging being pilloried unfairly

When it comes to the issue of plastics in the oceans of the world, images of waste usually appear in the media that give the impression that plastic packaging is the main cause of such pollution. This preconception does not stand up to closer scrutiny, though. Probably around half of the plastic debris in the world’s oceans is attributable to the fishing industry. The renowned environmental and animal protection organisation WWF even believes that the bulk of the plastic waste comes from fishing – in the form of nets, ropes, etc. And the WWF warns that a million tonnes of material like this is added every year.

According to experts, the low level of awareness of this serious problem is due in no small part to the fact that it is usually out of sight: the fishing gear left behind does not float on the surface of the water like empty plastic bottles, but instead travels the seven seas underwater or sinks to the seabed. This does not make them any less dangerous than the other rubbish in the sea, though – quite the opposite. Lines and nets form dangerous traps where fish, marine mammals, turtles and even birds can become entangled and meet an agonising end. Furthermore, fishing nets only decompose very slowly. Therefore, environmentalists and animal rights activists are warning against this type of plastic waste from fishermen, which, hidden from the eyes of the world, is responsible for a considerable part of the marine plastic waste problem.

Such old fishing nets are also called ‘ghost nets’, possibly because they are usually invisible or because they sail the seas like a ghost ship without a crew. This association with something spooky has an almost pleasant-sounding ring to it, but it nevertheless gives environmentalists the creeps: precisely because of the danger to wildlife and waters that ghost nets pose.

1000 kilometres of ghost nets a year 

And especially because of their sheer quantity. According to WWF estimates, about a third of all ropes and angling lines used for fishing worldwide are lost every year. It says that in European marine waters alone more than 1000 kilometres of fishing nets end up in a watery grave every year. The environmental organisation points out that this corresponds to a distance from the Baltic Sea to the Alps. The UN Food and Agriculture Organisation (FAO) estimates the figure to be even higher: it says 25,000 nets with a total length of 1250 kilometres are lost annually.

‘Lost’ is also sometimes a misnomer for the ghost nets. This is because such fishing gear is often deliberately abandoned, either when boats are caught fishing illegally or simply because of the high costs of proper disposal, which some fishing vessels cannot afford. Trawl nets can also get caught on objects on the seabed and become separated, though. Whatever the case, the drifting ghost nets, which are often kilometres long, pose an immense danger to marine life – and ultimately also to humans, because they decompose over centuries to form so-called microplastics and thus end up on our plates via fish.

In view of the risk that nets abandoned in the sea pose for the conservation of waters, the environment and animals, the WWF has now launched Germany’s first pilot project to recover ghost nets, in Mecklenburg-Western Pomerania. Within the framework of this project, the WWF will lead the search for, and recovery and disposal of ghost nets for two years using a method developed specifically for this purpose. It will work closely with fishermen and the authorities. The international nature and environmental organisation also explains that for the first time the authorities’ capabilities will also be used for the project, for example by using a state-owned ship for salvage. The pilot project will be financed with funds for the fishing sector administered by the coastal federal state. In addition, the Federal Environment Agency, together with the Federal Ministry for the Environment (BMU), is planning to support the WWF project regarding sonar searches in the North Sea and Baltic Sea as part of its funding for associations.

Using sonar to hunt ghost nets

The WWF is using state-of-the-art technology to search for ghost nets: sonar devices scour the seabed looking for the nets. According to the WWF, sonar is the most efficient way to find lost nets. This is because sonar can ‘see’ things up to 50 metres on either side of the ship. A sonar device scans the seabed with sound waves, creating a detailed picture of all the structures that are down there. Not only does it reveal rocks, sand waves, car tyres and barrels, but also ghost nets. This technique offers a special benefit: thanks to the sound waves, the seabed can be mapped and searched for ghost nets even when visibility is poor.

Political decision-makers now seem to realise that plastic packaging should not be blamed for the amount of plastic waste in the oceans. Mecklenburg-Western Pomerania’s Minister of Agriculture and the Environment, Till Backhaus, has announced a political initiative to solve the problem of ghost nets. This is because working on ‘cherished’ concepts of the enemy seldom helps solve actual problems. And that is why the WWF is clearly demanding that the search for ghost nets be made a matter that should be dealt with nationally.

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