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Compostable fishing nets: An end to ghost nets in the oceans?

‘Ghost nets’ lost from fishing boats become deadly traps for marine wildlife, persisting for centuries. Now a South African/Swedish joint venture aims at ending the problem with compostable fishing nets.


Fishing nets lost at sea are a major source of plastic pollution in the ocean. These so-called ‘ghost nets’ drift globally, ensnaring and killing fish, dolphins, seals, birds, and sea turtles. They can last up to 600 years, releasing microplastics as they slowly degrade.


Now South African initiative Catchgreen, is developing a solution. By creating nets and other gear from compostable Biodolomer, a net lost at sea would degrade into biomass within a few years. They also have a higher density so they will sink to the bottom of the ocean where they cause less harm and are subject to microbes that speed up decomposing. 


‘Biodolomer nets will not only reduce ghost fishing,’ said Emma Algotsson, project lead at Catchgreen and CEO of Kompost-It. ‘It will reduce the amount of micro plastics in the ocean. And old nets can be disposed of at industrial composting facilities and turned into biomass.’


Biodolomer was invented by packaging material legend Åke Rosén who has been instrumental in developing many materials for Tetra Pak and has over 65 patents to his name. It is produced and marketed by Gaia Biomaterials in Sweden since 2015 and is being used for everything from grocery bags to beer cups and agricultural cover films.


‘It is a material that has all the characteristics of plastic that a user wants – but is compostable,’ said Peter Stenström, CEO of Gaia Biomaterials AB.


‘Industries from all over the world are finding new uses for it. And we develop custom versions regularly. By changing the composition, we can for example change elasticity and how long it will take for the end product to decompose.

Unlike some bioplastics Biodolomer does not shed any microplastics and use a very limited amount of natural resources. In most Biodolomer products Limestone is a key ingredient.


‘Limestone is one of the most common minerals on the planet. And 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


‘In 2023, we conducted real world tests of gillnets in Kenyan waters. We 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 UK 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.


Picture courtesy: iStock/richcarey.


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