Nets and cages
A new approach
Chile-based company EcoSea says its nets are good for farmers, fish and the ocean
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ECYCLABLE copper submersible nets, pioneered by a Chilean company to rear fish “where it was not thought possible” in deep, high seas, will soon be available in the UK following successful tests. EcoSea’’s UR30 copper-alloy cage system minimises the use of nylon mesh, which the company describes as “the main source of pollution in the seas”. It is 100% recyclable and can be operated continuously for a decade. Copper alloy is also stronger than nylon, so it helps against predators such as sea lions and seals. “Over the past 12 years, EcoSea has deployed more than 70 of these systems around the world, growing more than 10 million fish,” the company says. “In addition, three farming centres in Chile were recycled after a decade of useful life, resulting in a total of 420 tonnes of recycled and resalable material.” At the heart of the new technology is the element copper, which has antifouling, antimicrobial, and anti-corrosion properties. Copper curbs biofouling, such as adhesion of algae, sea moss, sea anemones, barnacles, and molluscs. When these materials accumulate, they can block the flow of water and reduce the oxygen level in the net pen, while increasing pathogens and parasites. Preventing their accumulation helps reduce fish mortality, and improves growth and feed conversion. By halting the growth of organic layers in the cages, the copper alloy meshes “minimise the risky hours of diving and use of boats for cleaning, maintenance and replacement of traditional nylon nets, generating significant reductions in operating costs”, EcoSea says. Nylon netting typically must be cleaned by divers on a monthly basis, but with copper-alloy netting, the frequency of cleaning can be significantly reduced. Even when cleaning is performed, removal is easy, as attachment is weaker. The copper-alloy cages use a high-density polyethylene flotation system, which is also fully recyclable. “The recycling process stopped the use of 160 tonnes of nylon, the waste of 8,000 tons of fouling, which would have been deposited in landfills or on the seabed, and 184 tons of chemicals such as anti-fouling paint,” the company says. “It is estimated that the release of 10,300 tonnes of CO2 into the environment has been avoided so far.” However, some environmentalists see copper as a toxic chemical – is this a potential problem? “Environmentalists would not be wrong about the impact that copper coating/paints have on the environment, which is traditionally used on ny-
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Our “ submersible technology allows fish farming in open ocean waters
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lon or similar nets,” says EcoSea’s CEO Nicolás Castillo. “In our case, we do not utilise any coat or paint that flakes off over time and ends up in the bottom of the sea. Our technology utilises a copper-alloy mesh that does not flake off, and studies executed by independent labs have proven this does not affect the surrounding environment.” EcoSea says the copper alloy nets also show less volumetric deformation in high-energy, deeper water: “Under severe current and wave conditions, traditional fish cages experience substantial volume reduction due to deformation, generating overcrowding conditions, increasing the fish stress and mortality rate. Our technology maintains structural integrity and cage volume under adverse weather conditions.” The drawbacks of copper alloy are cost and weight. As for cost, the longer product life, reduced cleaning work, better fish health and end-of-life recycle value of copper tends to offset the initial cost, according to the company. The increased weight of copper means that flotation must be increased accordingly. However, in some situations, weight is a good thing as it keeps the net from losing its shape or tangling, especially in rough seas, the company says. Castillo says: “Our submersible technology allows fish farming in open ocean waters, where traditional cage technology doesn’t. By submerging the cages offshore, it is possible to avoid rough ocean conditions on the surface such as high waves and water temperature changes.” The antifouling characteristics of EcoSea’s cages material reduces the proliferation of pathogens and parasites within the fouling layer, while the ability to submerge provides an additional defence against sea lice, since they
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07/02/2022 14:46:21
