If you like to spend time along Germany’s North Sea coast, you will likely be well acquainted with weather, wind and waves. You’ll also be familiar with another sight: Small threads of plastic, mostly orange or blue, that have been washed ashore. These are so-called “dolly ropes” which are used to protect fishing nets that are dragged across the ocean floor. Many of these plastic threads get lost and drift through the oceans or onto the beach as plastic waste. But what exactly are dolly ropes? Why do so many of them break off and how do they impact the environment?
In this blog post, we’ll answer these questions and also look for potential solutions to this problem. You can probably imagine that we have some ideas in store, how we can upcycle dolly ropes into new products. Read until the end to learn more!
How do dolly ropes work?
Dolly ropes are used especially in bottom trawling. This involves dragging huge, funnel-shaped nets across the seabed, where they churn up entire ecosystems and catch everything that gets into their way. This extremely destructive type of fishing also takes its toll on the nets themselves. They chafe on the bottom or start to tear when they get caught on stony ground.
Fisheries have developed dolly ropes to protect their expensive nets. These are many small plastic threads made of polyethylene, usually about 1-2 meters long. They are put together in bundles and attached to the bottom of trawl nets in the middle of the bundles. When the nets are pulled across the seabed, the threads of the bundles splay out, forming a protective layer between the seabed and the fishing net.
How do the dolly ropes end up in the environment?
Dolly ropes are wear and tear items: they chafe, get entangled and in some cases, they also tear off. According to the Thünen Institute, a German federal research institute for fisheries, 10 to 25% of all dolly ropes are lost during their first two weeks of use. As a result, they require regular maintenance and replacement. This creates a perpetual cycle through which dolly ropes are lost every day and pollute the environment. And that’s not all. Due to poor waste management on many fishing boats, just as many dolly ropes end up in the sea again if they are not disposed of properly during maintenance work. That means, about 20 to 50% of all dolly ropes end up in the sea.
What does this all mean for the environment?
Dolly ropes are part of a particularly destructive fishing practice. Bottom trawling destroys the seabed irretrievably and has an enormously high bycatch rate. However, we want to exclude this larger criticism from this discussion, as we have already discussed some of it elsewhere, and now only focus on dolly ropes themselves.
Danger for animals
When plastic enters the environment, danger to wildlife is not far behind. Many animals confuse plastic with natural materials and dolly ropes are no exception. For instance, we can observe this on Helgoland, where Germany’s only colony of Nothern Gannet dwells. These birds collect dolly ropes to build or reinforce their nests. Many get entangled in the nets and cannot free themselves on their own, so they suffer an agonizing and slow death.
Plastic waste and microplastics in our oceans
Have you ever heard of the Great Pacific Garbage Patch? This huge garbage vortex in the North Pacific covers about four and a half times the size of Germany and consists of vast amounts of plastic waste. 46% of this consists of former fishing gear such as ghost nets and dolly ropes. It takes 400 to 600 years for such net parts to decompose in the oceans, and even then, only to microplastics. These are tiny plastic particles that irrevocably pollute seawater and are ingested by many marine animals as supposed food. With dolly ropes, marine pollution is pre-programmed: Their abrasion on the seabed creates this harmful microplastic all the time.
What can we do about this problem?
Dolly ropes exist to protect valuable material. That’s a good goal, of course – but not at the expense of the environment. That’s why we need alternative solutions to end this form of environmental pollution. What might that look like?
- Ending bottom trawl fishery This demand sounds drastic. But it has good reasons because bottom trawling is not only harmful to the environment because of dolly ropes. As the German Federal Agency for Nature Conservation explains with reference to the North Sea, the use of bottom trawls severely damages the seabed and leads to particularly high levels of bycatch, both of which have long-term consequences for ecosystems and species conservation.
- As long as bottom trawling exists, other materials could mitigate the negative environmental impact of dolly ropes. The Dollyropefree project in the Netherlands is testing alternatives that either better withstand abrasion on the seabed or are biodegradable. For example, solutions made of wood, hemp or leather come into question. In addition, dolly ropes that are biodegradable in seawater have been developed – but there are some reasons not to use bioplastics.
- Improving net designs Methods that eliminate the need for dolly ropes altogether would be even better – for example, new net designs that prevent any contact with the ground, thereby eliminating the need for abrasion protection. The Thünen Institute is currently developing such modifications, for example via the cutting of the nets or via buoyancy mechanisms.
- Improving fishery waste management Lastly, there is one point that fisheries can implement without much change or additional cost – their handling of trash. Raising awareness among fishing crews about the negative environmental impact of dolly ropes and their proper disposal could result in up to 50% fewer dolly ropes ending up in the oceans and on our beaches.
What about upcycling?
These proposed solutions all look to the future and want to prevent more dolly ropes from ending up in the oceans. But what about those that are already there? The answer is quite simple: We have to collect them. Then we can return them to the material cycle and recycle them. We have lately been working on an idea on how to upcycle them. We present our earrings made from dolly ropes!