Fish farming has gotten a bad rap recently, with horror stories of sewage and antibiotic dumping, water waste, overcrowded pens, and fast-spreading disease between farmed and wild fish pervading the media. But a new method of sustainable fish farming is gaining the confidence of producers and consumers.
The new method is RAS, which stands for Recirculating Aquaculture Systems. In an RAS system, large scale production is possible with little to no water pollution. In fact, 99.75 percent of the water used is cleaned and recycled back into the tank it came from. Waste can be filtered and distributed as fertilizer on nearby farms, or the "used" water can be transferred to aquaponics systems, where plants naturally filter the water, which can be taken back to the RAS.
RAS solves the problems pen farms, or crowded offshore enclosures, currently cause. Pen farmers don't pay for water like RAS farmers, simply because they use ocean water that's already there. This system might save money in the short-term, but the environmental costs over the long term are extreme. Concentrated groups of fish result in the repeated release of concentrated waste around the pen, along with clouds of antibiotics and fertilizers used to keep the close-quartered fish free of disease.
RAS is expensive up front ( a 92,000 square foot system run by leading U.S. company Australis Aquaculture had a start-up cost of $15 million.) But with the conservation community starting to demand producer responsibility for messes made throughout production cycles, the early costs of RAS are starting to look not-so-bad. Steve Summerfelt, director of the Conservation Fund's Freshwater Institute, says despite trepidation in our current economy, investors are starting to support RAS.