In addition to fish waste, antibiotics and other chemicals administered to the farmed fish can flow directly into the surrounding water. Disease is another environmental concern associated with net pen farming, as the crowded fish are susceptible to outbreaks that can spread to wild populations.
When Steve Summerfelt, who directs aquaculture systems research at Freshwater, began working on RAS development in 1992, his goal was to demonstrate that recirculating systems could produce healthy fish as quickly as traditional production methods.
After that was accomplished within a few years, his research – largely funded by the US Department of Agriculture – has focused on expanding RAS technology to larger scales that remain cost-competitive with other production methods.
That's no small challenge when competing against offshore fish farmers who don't pay for their water or face the constant expense of cleaning the water for reuse. But the efficient, cost-competitive RAS technologies developed at Freshwater and elsewhere are catching the interest of commercial fish farmers.
For example, Dr. Summerfelt says, his organization has been talking with about half a dozen fish farms that are considering investing between $5 million and $50 million in RAS production.
"Right now, [RAS] systems are not producing a tremendous amount of fish for the US," he says. "It's going to take these $5 million to $50 million investments to start seeing it happen."