Plastic is a necessary part of modern aquaculture. It is used in ropes, cages, feed bags and hoses, and it withstands the tough conditions at sea. However, we are aware that the plastics used in fish farming can cause problems as a result of wear and tear, is lost, or ends up where it shouldn’t.
Through SFI Dsolve, we work across several research disciplines in order to understand whether biodegradable plastics can be a good alternative in parts of the aquaculture sector. This was the topic when several of our researchers and industry partner SalMar recently participated in an episode of SINTEF’s podcast Smart Forklart. Together, they discussed opportunities and challenges by introducing new types of plastics in aquaculture.
A sea of plastic – and an opportunity for change
The aquaculture industry uses large amounts of plastics every year. Mooring ropes, cages, collars, walkways and other equipment remain in the sea for long periods, exposed to sunlight, saltwater and constant movement. This leads to wear – and sometimes to plastic being lost. The result is littering that gradually breaks down into micro- and nanoplastics and may affect marine life.
– It's not simple replacing everything overnight, says Maria Sparboe, Environmental Manager at SalMar. But we need to identify where change is possible, and perform practical tests of possible solutions.
“Biodegradable” doesn’t always mean sustainable
It’s easy to assume that all biodegradable materials are sustainable. As Cecilia Askham, senior researcher at NORSUS, explains, the reality is more complex:
– A material can be biodegradable but still have high environmental impact during production or release of unwanted substances during the degradation process. We have to look at the entire life cycle, not just the end point.
Life cycle assessments make it possible to evaluate how new materials affect the environment from production through degradation and provide a more complete picture of whether an alternative is better than the plastics commonly used today. This is why such assessments are a key part of the research carried out in Dsolve.
Technology that must withstand nature
Developing plastics that both endure harsh marine environments and degrade safely when their job is done is demanding, according to Christian Karl, researcher at SINTEF.
– We’re talking about an extreme environment – saltwater, UV exposure, biological growth and constant mechanical wear. Biodegradable plastics also need to function for years and at the end of its service time break down. This requires sophisticated material development.
For this reason, different polymers must be tested both in laboratories and in real marine environments to understand how they behave under realistic conditions, and how quickly they degrade.
Clear requirements build trust
The need for clear standards is important side of developing new materials.
Centre Leader Roger Larsen at UiT put it this way:
– Without shared requirements and documentation, anyone can claim their plastic is ‘green’. We need evidence, not just statements.
This is an important focus-area in Dsolve: contributing to clearer definitions, testing methods, and certifications so that both industry and consumers can trust that “biodegradable” truly means something.
From ideas to reality – the path toward better plastics in aquaculture
In Dsolve, we develop and test new biodegradable materials for fisheries and aquaculture. The goal is not to replace all plastics, but to find the right plastic for the right purpose and ensure that solutions that function well can be adopted by the industry.
Certain product types, such as single-use feed bags and frequently replaced ropes, may already now be good candidates for biodegradable alternatives. Other applications require more research and development to ensure that these materials can withstand the stress during use and that they degrade into safe end-products.
Life cycle assessments, material development and testing, both in laboratories and in the ocean, are closely connected in this work:
Life cycle assessments provide evidence on environmental benefits, material development creates new candidates of plastics, and testing determines whether they are durable in practical terms and serve the industry. Together, this makes it possible to develop solutions that are technically robust and genuinely sustainable.
In the long term, smarter material choices can reduce plastic pollution and strengthen the sustainability of aquaculture.
– The most important thing is that we really take action,” says Sparboe. “If we find the right solutions, and dare to use them, Norwegian aquaculture can become a leader in reducing negative impacts from plastics.