Aquaculture: copper alloy fish cages
Copper alloys in marine aquaculture are increasing productivity of operations. The copper alloys typically used are copper-zinc, copper-nickel and copper silicon.
Why choose copper alloy pens?
Due to their natural corrosion resistance, metallurgical and biological properties, certain copper alloys are the perfect 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.
1) Long life and recyclability
Copper alloy mesh lasts for five years or more depending on application conditions. It loses little mass over time and is fully recyclable. Recycled material is used in the 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.
2) Protection against predators and escape
High-strength copper alloy fish cages resist predator attacks and reduce escapes of farmed fish. They have also shown resilience against extreme storms.
3) Maintains pen volumes
Copper alloy mesh allows pens to maintain their shape better in strong ocean waves and currents. The resulting improvement in pen volumes prevents fish crowding and helps maintain high oxygenation that ultimately improves yields. The mesh also possesses high mechanical strength and formability, which are essential in the manufacturing of effective marine aquaculture containment structures.
4) Improves fish health and production
Copper alloy mesh limits the costs, fish stress and nuisance of net changes. The increased water exchange and dissolved oxygen compared to other materials improves fish health and growth. Feeding costs can be reduced by 15%. The habitat for parasites and pathogens that infect fish is also much reduced.
5) Reduces maintenance
Cleaning is reduced and copper alloy meshes do not need to be removed to carry out the process. This lowers diver hours and risk as well as overall costs associated with maintenance.
Current use and future applications
Copper alloy mesh technology began in 1975 with small salmon farming enclosures in north-eastern USA. Since then, alloy technology has evolved and is now being used in Australia, Canada, Chile, China, Greece, Japan, Korea, Mozambique and Scotland, providing productive and sustainable solutions for fish farmers.
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 building 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, etc.
On average, copper alloy cages must be cleaned approximately once or twice a year, which is significantly fewer than traditional cages, over a service life.
Copper alloys can be used for current cage designs as well as other future, more cost-effective designs and applications. Today, it can replace round HDPE cages, and square steel cages with and without platforms. Trials using the Aquapod 3600 and the OCAT cages with copper mesh are currently being conducted, and the Ocean Spar 3000 submersible cage is in prototype discussions.