VANCOUVER -- Critics of open-net fish farms say the escape of 305,000 Atlantic salmon in Washington state should spur Canada to support a transition to land-based aquaculture.

Steve Summerfelt of the Conservation Fund Freshwater Institute in Shepherdstown, W. Va., says compared with the United States, Europe and China, Canada has the most companies using closed-containment pens to harvest salmon.

He says four of the world's 13 land-based facilities are in Canada, while China has the largest production capacity, followed by Denmark.

Summerfelt says while the technology to grow fish on land-based farms has steadily improved, relatively high capital and operating costs have been a challenge to the widespread implementation of that model.

Bob Chamberlin, chairman of the First Nations Wild Salmon Alliance, says the Washington state spill earlier this week near B.C. waters requires government and industry to back more sustainable ways to farm salmon, which is in such high demand around the world.

He says waste being pumped into the ocean from open-net salmon farms is harming the environment and those costs aren't absorbed by companies producing salmon in more profitable but less sustainable ways that threaten wild species.