The environmental promise of open ocean fish farms

Innovative submersible fish pens and new developments in fish food may change the way “fish farming” is conducted throughout the world. Sustainable aquaculture is possible, say some innovative practitioners — and open ocean fish farms may be the solution to a whole range of environmental problems.

These are not the crowded, close-to-shore pens where fish are trapped like caged chickens, requiring doses of antibiotics that leak, along with the concentrated wastes, into surrounding waters. They are submersible net pens, more than 150 feet apart, where ocean currents disperse waste, and fish swim and live in the closest possible approximation to their natural habitat. In a word: free-range fish.

And the food the fish can be fed — developed from soy and microalgae instead of feeder fish like the Peruvian anchovy that underwent a major collapse in the 1970s — has potential for removing fish altogether from the meal equation.

The Problem with Commercial Fishing

The majority of commercial fishing operations today rely not on fish farming at all but on trawling for their catches — dragging a massive net, up to a football field in length along the sea floor or midway between the floor and surface. Not only do these nets sweep up desired species such as pollock, cod, flounder and shrimp, but a significant amount of unsought species –known as bycatch — that die but then get thrown back as waste. Greenpeace International reports that bycatch — which can include whales, dolphins, sharks, porpoises and turtles — could comprise anywhere from 8% to 25% of global catches,

These destructive operations, along with pollution, ocean acidification and global warming, have sent wild fish on a dangerous downward spiral, with no signs of recovery. Predator fish — including sharks, swordfish and cod — are already 90% gone. The U.N. reported in 2010 that 30% of the world’s fish stocks were similarly wiped out and said that, if current fishing rates continue, the world’s oceans could be fishless by 2050.

But conventional, large-scale fish farming operations — particularly those on shorelines where fish and their waste are confined — come with serious environmental concerns, too, largely for concentrating pollution in coastal waters. Also, when farmed fish escape they can quickly upset the ecological balance, such as happened with the blue tilapia, which is now a major threat to freshwater species in the southern Gulf States. Its population explosion has led to mussel declines and tends to wipe out vegetation and all other fish in streams where it becomes established. Farmed salmon, too, have for years escaped their pens in British Columbia and Washington State, finding their way to Alaska in recent years and presenting a concern that they’ll begin to push out the native Pacific salmon.

New Approaches

The answer may lie in fish farming using a submersible fish pen called the Aquapod by Ocean Farm Technologies. It can be lowered into deep water hundreds of feet from shore, below the wave action, allowing fish to live in their natural habitat and providing a means for fish waste to disperse naturally. Fish are fed by a barge boat that pumps a mixture of food and water from hoses into the cages.

The technology is continually evolving to incorporate more automation, allowing for faster cleaning and servicing and enabling them to be pulled by a cable and boat.

In Hawaii, Neil Sims ran a company that was putting the Aquapods to use growing kampachi — sashimi-grade yellowtail. After a trial-and-error period with various species he found that farming kampachi in the Aquapod is as straightforward as sheep farming. The fish thrive in the enclosures and take readily to food pellets that are being increasingly developed with minimal fish meal.

The hope of sustainable aquaculture advocates, including Sims, as well as Robert Orr, whose Cuna del Mar firm supports Ocean Farm, is that these submersible pens will present a new vision of 21st century farming — raising fish in a way that leaves minimal impact or even enhances the natural marine environment while allowing wild fish stocks to recover.

But the U.S. is not poised to launch a new sustainable aquaculture industry using submersible net pens. According to Michael Rubino, director of the Aquaculture Office at the National Oceanic and Atmospheric Administration (NOAA), there have been “10 years worth of legislative proposals in Congress trying to do it” under the Magnuson-Stevens Act, which governs catch limits, requires the government to work with regional councils on upholding environmental standards and authorizes councils to establish zones to protect corals. A regulatory framework for deepwater fish farms will have to be incorporated into this act, and it’s something that the Gulf of Mexico Fishery Management Council is working on.

Feeding a Growing, Hungry World

The world’s population will grow to nine billion people by 2050, with an appetite to match. Even just to maintain today’s level of fish consumption will require another 23 million tons of farmed fish by 2020, according to the Worldwatch Institute. By 2030, the United Nations Food and Agriculture Organization says we’ll need an additional 40 million tons. In 2011, a record 154 million tons of fish were raised and caught — by 2020, 60% of the world’s fish is expected to come from aquaculture.

People in the U.S. like to eat seafood, but the country produces very little of it. Ninety percent of seafood eaten in the U.S. is imported, Rubino says, and about half of that is farm-raised. Shellfish make up 80% of what fish farming there is in the U.S. The other big industry is salmon farming with operations in Maine and Washington State, although aquaculture in some form can be found in all 50 states, including catfish farms in Mississippi and trout farms in Idaho.

“Seafood is by far the most efficient protein to grow but you’ve got to be able to do that in a way that honors the rest of the environment,” says Orr. “Doctors and nutritionists are asking us to eat more seafood,” agrees Rubino. “And where’s that going to come from?”