New predator nets on trial

Canada: Mainstream Canada announced that the first fish have been entered into copper nets as part of a research trial- the first such nets to be used in North America

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Odd Grydeland

The Plover Point farm site where the nets are being deployed is the most recent location to be approved for salmon farming in British Columbia, getting the nod in October last year. It is located in Clayoquot Sound on the west coast of Vancouver Island, where Mainstream has another 13 farm sites. The area gets inundated with an increasing number of California sea lions and also Steller sea lions every year. Episodes of entanglement and drowning of sea lions trying to get into conventional nylon nets has spurred a number of initiatives to try to keep the predators at bay. Creative While Salmon Company has managed to develop an effective barrier between its salmon and the sea lions by using double nylon netting, Mainstream Canada recently announced that the company has started a research project using fence-like predator nets made of copper;

Key Highlights:

• Two copper-alloy net pens have been installed at a salmon farm on the West Coast of Vancouver Island, B.C., Canada.
• Copper-alloy net pens protect farmed fish and act as an effective, passive deterrent to predators such as seals and sea lions.
• Copper- alloy net pens stay naturally clean while maintaining maximum water exchange.
• This is the first copper net pen installation in North America.

The International Copper Association (ICA) and EcoSea (a Chilean developer of copper-alloy aquaculture systems) recently installed two copper-alloy net pens off the west coast of Vancouver Island, B.C., Canada, for Mainstream Canada. Each pen has been being stocked with 52,500 Atlantic Salmon. The pens measure 30 x 30 x 11 meters, are constructed from 13 tons of copper-alloy mesh, and have a growing volume of 10,000 cubic meters. The pens were assembled and installed in December 2012 at Mainstream Canada’s Plover Point farm, which is a short boat ride away from Tofino, B.C. The installation was completely conducted in water. Traditionally, installations start on the beach.

Langley Gace, aquaculture applications development manager for the ICA, stated, “Marine mammals present a challenge to fish farms in British Columbia. It can be very costly for farmers to keep fish safe and healthy. Copper-alloy mesh will not only protect the fish stock but also protect seals and sea lions.” Brock Thomson, Mainstream Canada’s projects manager, said, “The deployment of these copper nets is part of a two-year comparative study between nylon and copper mesh. We are eager to see how the study evolves. We’re hopeful they will be effective in staying naturally clean, minimizing our environmental impacts, and eliminating interactions with marine mammals.”

Mainstream Canada chose to install copper-alloy net pens because copper’s natural properties prevent the growth of organic matter such as seaweed and mussels, a serious concern with conventional nylon nets because organic matter can block water flow and deplete dissolved oxygen in the water. Copper-alloy mesh stays naturally clean, resulting in lower maintenance costs and a healthier environment for fish. They have also been shown to release very little copper into the ocean environment. All copper-alloy net pens are 100 percent recyclable.

In addition, Mainstream Canada believes copper-alloy net pens will be a strong, passive deterrent to marine predators. Mainstream currently installs nylon predator nets at all farm sites—secondary nets that are placed around a farm’s entire perimeter to keep out seals and sea lions. Predators can sometimes still bypass the predator nets and the nylon net pens inside. Copper-alloy cages will make it nearly impossible for predators to get into the fish pens and will eliminate the need for costly, secondary predator nets.