Copper Alloys Increase Operational Productivity in Marine Aquaculture
Due to their corrosion resistance and mechanical properties, copper alloys are ideal materials for both surface and submersible marine aquaculture enclosures for near- and off-shore sites.
Copper alloy mesh aquaculture pens improve the sanitary conditions, productivity and sustainability of operations for farmers raising salmon, trout, sea bream, sea bass, cobia, yellow tail and other species. The mesh possesses high mechanical strength and formability, which is essential in the creation of effective marine aquaculture containment structures.
Exclude Predators and Prevent Escapes
The high-strength copper alloy mesh resists predator attacks and eliminates escapes of farmed fish, decreasing the direct economic cost to fish farmers and preventing the ecological impact of any interbreeding with wild fish stocks. It has also shown resilience against extreme storms.
Improve Fish Health and Production
Copper alloy mesh provides structural stability that allows pens to maintain their shape and volume better in strong ocean waves and currents, even those offshore. This prevents fish crowding and improves water flow and circulation, which helps maintain high oxygenation. The conditions within the copper alloy mesh pens improve fish health, increase growth and development, lower mortality rates, improve feed conversion and ultimately improve yields. With improved conditions, the need for antibiotic and anti-fouling chemicals is reduced.
Copper alloys exhibit low macro-organism attachment in seawater so mesh rarely needs to be cleaned and routine net changing is eliminated, lowering overall costs associated with maintenance as well as reducing diver risk.
Long-lived and Recyclable
Copper alloy mesh lasts for six years or more depending on application conditions. It loses little mass over time—due to corrosion resistance—and is fully recyclable. Recycled material is used in initial production of copper alloy mesh, which further reduces CO2 emissions, compared with traditional polymer nets. High-strength and corrosion-resistant copper alloy meshes are compatible with pens commonly used in the marine aquaculture industry, allowing for rapid implementation at existing grow-out centres.
Current Use and Future Applications
Copper alloy mesh technology began in 1975 with small salmon farming enclosures in the north-eastern USA. Since then, alloy technology has evolved and is now being successfully used in Australia, Canada, Chile, China, Greece, Japan, Korea, Mozambique, Scotland and the Seychelles, providing productive and sustainable solutions for fish farmers. Copper alloy mesh is also being applied to innovative aquaculture solutions, such as ocean farming vessels.
Three alloys are currently commercially available: copper-zinc, copper-nickel and copper-silicon.
Copper-zinc is good for flexible mesh containment systems.
Copper-nickel is good for rigid (e.g. welded) mesh.
Copper-silicon is good where rigid mesh is needed, or where panels can have flexible connections.
After exposure to seawater, copper alloys develop a surface oxide film which provides protection from corrosion.
Copper alloy mesh can easily be used for all current commercially-available cage designs as well as other innovative fish cage systems.
Copper alloys can harbour slimes, but the attachment of macro-organisms—such as marine grasses and shellfish—is impaired. If these do become attached under quiet conditions, adherence is poor and they can be easily removed mechanically.
The exact cost of using copper alloys in aquaculture enclosures depends on multiple factors such as the cage size and the transportation of materials to the construction site, and then of the cage to the farming site. Overall, the total cost is offset by the long-term cost savings associated with longer service life, decreased fish losses, lowered maintenance, improved Food Conversion Ratio and reduced health costs.