Land-based farming is way too expensive. The energy costs to pump the water are prohibitive.
In the land-based systems that are currently set up for rearing of salmon fry, water is almost entirely recirculated within a closed system. Only minimal amounts of water need to be supplied to the site and because it's freshwater, it can be gravity fed.
Salt water will always have to be pumped up to the site. I highly doubt there are adequate recirculation systems to handle the biomass and water requirements of hundreds of thousand adult salmon. Let alone systems that could stand up to the relentless abuse of saltwater. Ocean-rearing on land would therefore require constant pumping of water to the site, that would then be filtered, and returned to the ocean.
In-ocean closed-containment is the only option the industry would consider viable. The energy requirement for the system can be lowered to within a reasonable percentage of total costs. There is a pilot study already underway.
http://www.sustainable-aquaculture.ca/The project looks promising. One point of concern is that not all water used for the system is treated. In fact, up to 60% of water from the pens spills over the top and into the ocean untreated. The ocean water originates from deep intakes so parasites shouldn't be a problem, but disease is still a possibility. Generally speaking however, farmed salmon are healthier and carry fewer pathogens than wild salmon.
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Topic: Save BC Salmon (Read 6366 times)