6 minute read
Tackling the plastic challenge
by SeafishUK
Tackling the plastic challenge
What can be done to help reduce plastic waste?
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By Marta Moran Quintana
Leo Baekeland, chemist, wrote on his diary on 11 July 1907. The invention to which he referred was a synthetic polymer he called Bakelite, the precursor of modern plastics.
Baekeland was not mistaken. Begun in the 1950s, mass production of plastics did indeed change the future. From keeping food fresh longer to making disposable syringes, plastics transformed our world, and fishing was no exception.
Before plastic, fishing nets and pots were traditionally made of natural materials such as willow, wood, linen and hemp. The new synthetic plastics quickly replaced all these materials and the new fishing gear was stronger, lighter weight, more durable and cheaper. Before long plastic fishing gear had taken the fishing industry by storm.
Nigel Legge, Cadgwith
As early as 1959, synthetic nets were described as “a revolution in modern fishing”. Nigel Legge, skipper of the Razorbill (SS268) in Cadgwith, recalls how he used to make his own willow pots, but stopped the moment that the new plastic pots came out.
“I just threw all my tools in a corner and didn’t touch them again for twenty-odd years”, says Nigel. “Plastic lasts longer and can work in ways that willow won’t allow.”
The days of artisanal gear-making were coming to an end, and plastic gear became the norm.
Today, plastics are everywhere, often even in places they were never intended to be. A University of California research team estimated in 2017 that humanity has produced over 8 billion tonnes of plastics since 1950, over three-quarters of which has ended up as waste.
Unfortunately, much of that waste finds its way into the sea. The same California research team estimated that in 2010 alone, between 4 million and 12 million tonnes of plastics ended up in the ocean. Some of that waste is fishing gear, estimated to make up a tenth of all marine litter. Fishing gear lost at sea is known as “ghost gear” and can persist in the environment, where it continues to catch fish, from which nobody benefits.
Plastic has become a victim of its own success. The very same characteristics that make plastics ideal for packaging, construction and fishing gear—versatility, durability and resistance—also make them a serious environmental issue.
Plastics in the environment can take hundreds of years to degrade in the ocean, where they break down into micro plastics that marine life can ingest. This presents a major problem for the fishing industry. Long credited as a healthy protein, there is now a risk that consumers may lose confidence in seafood because of micro-plastic contamination.
Micro plastics made headlines in the UK recently as researchers from the University of Plymouth reported finding tiny plastic pieces in a third of the fish in a sample caught in the English Channel. The public and regulators are becoming increasingly aware of the problem of plastic pollution, and in 2018 DEFRA launched a consultation to gather views on tackling pollution from single-use plastics. Launching the Conservative Party’s new environmental plan in January, Theresa May pledged that the UK would eliminate avoidable plastic waste by 2042. In the near future, we’ll likely see new legislation to control plastic waste.
Projects are already underway around the world to reduce plastic waste from fishing activities. In 2017, the UK and Scottish governments joined Global Ghost Gear Initiative, an international initiative to reduce the amount of derelict fishing gear at sea. Society is clearly urging that something be done about plastic pollution in the ocean—but what can the fishing industry do?
Going back to pre-plastic times is not a viable solution. Natural materials are less durable, and fishermen would need to spend more time and money repairing or replacing gear. Furthermore, the fishing industry has changed significantly since the 1950s, making traditional gear no longer suitable.
Nigel still makes willow pots, but not for fishermen to use at sea. “These pots are probably better than plastic ones, but they were designed for very small boats hauling by hand. They wouldn’t survive the way big vessels work. I went back to making them just because someone asked me for a pot to decorate their garden.”
What if there was a material as durable and resistant as plastic that doesn’t break down into a harmful substance when it degrades at sea? Could a safe, biodegradable material replace plastic fishing gear? That’s precisely what Eduardo Grimaldo, fisheries researcher at SINTEF (Norway), is working on.
Grimaldo, his team and the industry are trialling biodegradable gillnets that could help reduce the problem of ghost gear.
“There is interest from the Norwegian fishing industry in using more environmentally friendly materials”, Eduardo explains. He is particularly interested in the fleet catching Greenland halibut, whose gillnets, deployed at great depth, are difficult to recover if lost or tangled.
Eduardo and his team are trialling nets developed in South Korea, where the local fishing industry has been using them for around 10 years. Norwegian fishermen helped modify the nets to suit their needs and trialled them over two years on commercial fishing vessels covering the entire fishing season for halibut, saithe and cod.
In the trials, conventional nylon nets and biodegradable nets were deployed side by side to compare their performance. Early results showed that the biodegradable nets had lower catch rates than standard nylon nets, around 10-15% lower in terms of number of fish caught. Nylon nets were also better at catching bigger fish, likely because the biodegradable nets were slightly more susceptible to wear and tear and degradation.
Could biodegradable nets be a solution then? Although the first trials showed lower catch rates from biodegradable nets, Eduardo and his team are not ready to give up. He believes they show huge potential, and that with more research and innovation they will be able to create a safe biodegradable net that is as effective as conventional nylon. He says, “Fishermen tell us they would be happy to use these nets, but the lower catching efficiency is an issue for them.”
Cost could be another issue. At present, alternatives to plastic are expensive. The nets purchased for the trials cost about twice as much as standard nylon nets. However, Eduardo noted the biodegradable nets are much cheaper in South Korea, where the demand is higher than in Norway.
New materials are always more expensive at the start of the production process because of the basic law of supply and demand. But phasing out and replacing plastics in coming years would cause alternative materials to become more widely available and cheaper.
Eduardo is planning further trials for late 2018, when the team will test a new biodegradable net made of thicker filaments. They believe this new design will show improved strength and efficiency, comparable to standard nylon nets. There are also plans to trial biodegradable rope — the Norwegian aquaculture and fishing industries use around 22,000 tonnes of plastic rope every year, much of which gets lost at sea.
Back in the UK, research to reduce plastics in fishing is taking a slightly different approach. Instead of removing plastics from fishing gear altogether, some net designers are looking at different ways of constructing nets that require smaller amounts of plastic net and rope.
Dolly rope on a beam trawl
One particular type of plastic waste from fishing gear is attracting attention from researchers and net makers: dolly rope. With threads around 2m long, dolly rope is widely used on North Sea demersal vessels to protect the cod end against friction with the seabed.
The DollyRopeFree project in the Netherlands estimates that up to a quarter of the dolly rope used in a trawl will tear off and end up in the sea. An estimated 25 tonnes of dolly rope enter the North Sea every year as plastic waste.
Darren Edwards, from Brixham Trawl Makers, told us about their new trawl design that uses drastically reduced amounts of dolly rope. The first step was to increase mesh size in the trawl, which alone helped to cut the amount of dolly rope used by a third. As Darren explains, “If you have a bigger mesh, you have fewer meshes in the trawl to put the rope through.”
In recent years, Darren and his team have managed to further eliminate the need for dolly rope by reshaping the trawl. “We used to have a lot of the net sitting on the bottom; now, it sort of cylinders so that only a few meshes go across the seabed. If you put dolly rope there, it would just drag the net down, so we took it out—and it works.”
For the last few years, several vessels in Devon have been using this trawl design, not only reducing plastic pollution but also saving them money. Darren explains, “Previously you had to cut up the old ropes and put new ones in; now, it is cheaper to cut a piece of net and replace it. All the net we cut here then goes into a recycling sack.” Other fishermen in Cornwall are using similar designs of their own.
Leo Baekeland was right when he predicted his invention would change the future. What he probably did not imagine was the challenges it would also bring over a century later. Those challenges are for us to solve, and the fishing industry’s skills and determination to protect the seas will be essential to addressing them.
