Ghost nets lost from fishing boats become deadly traps for marine wildlife, persisting for centuries. A South African and Swedish joint venture aims to end the problem with compostable fishing nets.
Fishing nets lost at sea are more than just a major source of marine plastic pollution. Known as ghost nets, they also form a hazard to ocean life. As they drift globally, they ensnare and kill fish, dolphins, seals, birds and sea turtles. They can last up to 600 years, releasing microplastics as they slowly degrade.
A South African initiative called Catchgreen believes it can deliver a solution. Typically, fishing nets today are made of fibers from high density polyethylene, PET or nylon. Catchgreen is collaborating with Gaia Biomaterials in Sweden on the production of fishing gear from a compostable polymer called Biodolomer. A Biodolomer net that is lost at sea would degrade into biomass within a few years. Because of the material’s higher density, Biodolomer fishing nets and gear would also sink to the ocean bed, where they cause less harm and encounter higher quantities of microbes that speed up their decomposition.
According to Emma Algotsson, project lead at Catchgreen and CEO of Kompost-It, Biodolomer nets will not only reduce ghost fishing but also the volume of microplastics in the ocean. “And old nets can be disposed of at industrial composting facilities and turned into biomass,” she added.
Unlike some bioplastics, Biodolomer does not shed any microplastics and uses a very limited amount of natural resources. In most Biodolomer products limestone is a key ingredient.
The material was invented by leading packaging materials scientist Åke Rosén and has been produced and marketed by Gaia Biomaterials — the company he founded — in Sweden since 2015. Applications for the material range from grocery bags to beer cups and agricultural films.
“It is a material that has all the characteristics of plastic that a user wants, but is compostable, says Peter Stenström, CEO of Gaia Biomaterials AB.
New uses are being found for the material by industries the world over, he added. Moreover, it can be customized to meet the specifications of any particular application. “By changing the composition we can, for example change elasticity and how long it will take for the end product to decompose,” said Stenström.
Limestone is one of the most common minerals on the planet. When Biodolomer decomposes, it becomes water, CO2, and soil enriched with calcium carbonate."
Developing compostable fishing nets has been challenging. Emma and Gaia Biomaterials' team have dedicated years to creating a suitable substrate for the threads used in larger nets, collaborating closely with South African net producers. The partners conducted real-world tests of gillnets in Kenyan waters in 2023 and are also working on biodegradable ropes and nets for coral restoration, seaweed and kelp harvesting. The ultimate goal is to trial the material for trawl nets.
Catchgreen is in part financed by The Sustainable Manufacturing and Environmental Pollution (SMEP) programme under the United Kingdom Government. SMEP is implemented in partnership with the United Nations Conference on Trade and Development (UNCTAD). Catchgreen fishing nets are set to hit the market in 2024.