Plastic litter is a serious problem affecting the marine environment, with current estimates indicating there is anywhere from 27 to 66.7 million metric tons of plastic currently in the world’s oceans and rivers. That number now grows every year by more than 12 million metric tons, notes environmental consultancy Eunomia and the resulting ecological, social, and economic costs are considerable.
Three-quarters of marine plastic litter (74 percent) originates from land, 9.4 percent from fishing litter, 7.8 percent from primary microplastics, and 4.9 percent from shipping litter, Eunomia reports.
Traditionally, waste plastics from aquaculture and capture fisheries have been considered together, but the Aquaculture Stewardship Council (ASC) believes that this is not helpful to the industry, as the causes are different.
A great deal of attention has been paid to how much abandoned, lost, and discarded fishing gear, as well as ghost fishing, entanglement, and habitat damage contribute to marine plastic litter levels. However, less emphasis has been placed on understanding the plastics issue as it relates to aquaculture, according to a new ASC white paper, Marine Litter and Aquaculture Gear.” In the paper, the ASC sets out to address this imbalance, by classifying the different causes of plastic waste from aquaculture, and assessing the risks to different farming systems.
The white paper is timely, given that aquaculture already supplies more than half of the world’s seafood, and the industry will gain greater importance over the coming decades, as the global population increases and wild marine resources remain at current population levels or diminish, ASC Standards Coordinator Marcelo Hidalgo told SeafoodSource.
ASC’s research found that aquaculture makes extensive use of plastics for both equipment and packaging, with plastic materials used in everything from polystyrene foam-filled fish cage collars and polymer-coated cage nets to plastic harvest bins and feed sacks.
The study looked at more than 60 ASC-certified farms that use ocean water cages and pens, inland ponds, and suspended rope and cage systems. It found that the most likely causes of plastic loss were extreme weather, poor waste management, and installation wear, and failure resulting from poor siting or lack of maintenance.
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