STUDY REVEALS ENVIRONMENTAL PROBLEMS CAUSED BY DISCARDED FISHING ROPES AND LINES

Study reveals environmental problems caused by discarded fishing ropes and lines. For the first time, researchers have investigated how ropes and fishing lines are handled by the Norwegian commercial fishing industry. The fishing fleet loses almost 400 tonnes of rope in Norwegian waters every year.

Lost fishing lines and ropes are a growing problem. As a leading fishing nation, Norway, with its long coastline and fish-rich waters, is particularly vulnerable to marine litter. A new study from NTNU shows that only a third of all ropes produced and sold in Norway can be recycled in a sustainable way.

The rest are burned, buried, sent out of the country – or just pile up and contribute to something called ghost fishing.

“Norway is heavily dependent on the blue economy, and finding solutions is becoming increasingly urgent.  Without the responsible handling of ropes, the fisheries sector will never be green or sustainable,” says Associate Professor Paritosh Deshpande at NTNU’s Department of Industrial Economics and Technology Management.

He studies plastic litter in the ocean, and has made the first scientific estimates to establish how much rope is lost and how the Norwegian fisheries sector handles ropes.

The researchers have analysed 15 types of rope widely used by professional fishermen in Norway. They have also ranked the rope according to how easy or difficult it is to recycle.

The goal is to develop new knowledge and tools that can contribute to less litter, more recycling and increased sustainability. Deshpande has been working on this problem for the last eight years. His previous research findings have been used by the UN Environment Programme and other agencies in the UN, the EU system, the Norwegian Environment Agency and others working on policy in this area.

Only in the last decade have we realised that we have made the oceans the world’s largest rubbish dumps. An article in Science estimates that between 5 and 13 million tonnes of plastic end up in the oceans each year, but there is no global data on how much of that comes from marine industries.

For several years, Deshpande has collected data from Norwegian suppliers, manufacturers, dealers, fishermen, waste disposal sites, recycling companies and authorities. The collection has been repeated several times to remove uncertainty and ensure that the data are correct.

What he sees is that different manufacturers make the same types of rope and fishing gear, but in different ways and out of different materials. Many manufacturers don’t know exactly what kind of or how many different plastics their ropes contain. The methods vary, and imported raw materials may lack content labelling.

“If you buy a bottle of water, you can find out exactly how much calcium and magnesium it contains. You don’t get this kind of information when you buy fishing rope,” he points out.

An overview of the 15 most used ropes shows what they are made of, how they are made, what they are used for, and any special characteristics they have. The researchers have divided the ropes into three categories, with easy-to-understand traffic light colours according to their recyclability.

This could be the first step towards a labelling scheme where manufacturers divide ropes into categories. Labelling can contribute to used ropes being treated more as a valuable resource, the researchers believe.

Other measures may include:

• Research and innovation for more eco-design and recyclability
• Smarter return schemes
• Best-practice schemes for handling ropes
• Increased efforts to get plastic manufacturers to use recycled plastics

“Manufacturers, fishermen, authorities, waste disposal sites and recycling companies. All of them can be part of the solution, and none of them can do it alone. This also involves UN Sustainable Development Goal number 17, which is about us only being able to achieve the goals if we work together,”  Deshpande says.

Waste is dangerous to wildlife that lives in and by the sea. It traps, injures and kills – and enters the food chains.

Deshpande is working to ascertain the scope of this, with Norway and the Norwegian fisheries sector as his starting point. He believes that if we are to make a green shift in the blue industry, the production cycle must be closed and the hazardous waste moved into a circular economy. In a circular economy, products must last as long as possible, be repaired, upgraded and be reused to a greater extent. When products cannot be reused, the waste material can be recovered and used as raw material in new production. In this way, the same resources can be used several times and as few as possible are lost.

To do that, we need to know what kind of plastic has gone astray, and how much is available for recycling.

“We then need to ensure that the possible solutions are environmentally friendly, socially acceptable and feasible,” he says.

In 2019, Deshpande and his colleagues published an article about the most deadly plastic waste that ends up in the ocean: fishing gear that has been forgotten, abandoned or lost.

“We conducted a material flow analysis that showed that almost 400 tonnes of this type of waste from the Norwegian fisheries sector end up in the sea every year,” says Deshpande.

A material flow analysis is a systematic assessment of flows and inventories of materials within a given system defined in space and time. Having good documentation of material flows is a prerequisite for good resource and environmental management of given substances or materials.

Crab pots, long lines, nets and fish pots get left on the seabed and continue to catch fish and other sea creatures. This macabre form of fishing can continue year after year.

In the long run, this littering also means that the fisheries end up undermining their own industry.

Rope was not included in this study, but it is the focus of Deshpande’s article, published in the Marine Pollution Bulletin. Studies also need to be conducted into how much the fish farming industry contributes to the problem.

Deshpande says that the figures they have indicate that Norwegian fishermen fill Norwegian waters with almost 800 tonnes of plastic fishing gear and ropes – every single year.

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