By David Helvarg
Thanks to high-tech cages and a better understanding of fish biology, aquaculture is moving offshore and into the open ocean.
Peering through the taut weave of polymer netting, a diver could easily believe the sea holds a limitless supply of fish. Inside the submerged cage, tens of thousands of sleek carnivores rub fins as they navigate their saltwater territory. Yet, the Pew Oceans Commission reported two years ago that global oceans are in crisis. Wild fish populations have diminished under human demand. Because of new technology, however, marine species once pushed to the edge by nets may soon proliferate within them.
According to the Food and Agriculture Organization of the United Nations, 44 percent of the world’s fisheries are heavily to fully exploited; another 25 percent have been fished beyond sustainable limits. The farming of finfish, shellfish and aquatic plants, on the other hand, is a global industry growing at nearly 9 percent a year. One-third of the world’s seafood supply is now farm-raised; half of global fish production is projected to come from aquaculture in the next 25 years.
“The demand for seafood is on the rise,” says Michael Rubino, aquaculture program manager for the National Oceanic and Atmospheric Administration (NOAA). “Currently, over 70 percent of the seafood that Americans consume is imported. This has led to an almost $9 billion trade deficit.” The National Offshore Aquaculture Act, slated for introduction to Congress this summer, may reduce that imbalance. It would give NOAA the authority to license fish farms in the U.S. Exclusive Economic Zone–nearly 4.5 million square miles of federal waters extending 200 nautical miles from the coast.
The template for aquaculture in the open ocean now exists in the top-shaped submersible tethered 2 miles off the island of Culebra in Puerto Rico. The cage’s 50-ft.-tall steel mast, or spar, is attached to a 25,000-pound concrete block resting on the seabed 93 ft. below the surface. A steel rim 85 ft. in diameter supports a wall of Spectra netting-all that separates the 15,000 fish inside from circling sharks. After a year, the 12-pound cobia–raised from 6-week-old hatchery stock weighing less than an ounce–will be shipped to markets in Florida and New York.
Snapperfarm, which owns this cage and another off Culebra, is one of three U.S. companies operating commercial fish farms offshore. The oldest is Cates International, established in 2000. The company’s four cages, located 2 miles off the Hawaiian island of Oahu in water 150 ft. deep, hold 700,000 moi–an overfished, local favorite. Kona Blue Water Farm, the newest outfit, recently obtained permits to raise its own breed, Kona Kampachi (related to Japanese hamachi), in six cages off the Big Island of Hawaii.
The University of New Hampshire is running its own offshore experiment, raising haddock, Atlantic cod and halibut in spar-net cages 6 miles off the New England coast. “The farm of the future is going to be submerged,” says Rich Langan, director of the school’s Open Ocean Aquaculture Project. “So we want to develop and demonstrate technologies for commercial application.”
Langan and his colleagues recently engineered a feeding buoy that can hold a week’s worth of food. Operated remotely, it will eliminate the current practice of boat-based operators feeding fish through hoses. “There is going to be a lot of innovation in cages, and feeding and operational systems,” he says, “and wireless technology is going to play a major role.”
Not everyone is convinced that technological leaps will eliminate the problems plaguing other forms of aquaculture. Coastal salmon farms, in particular, have been criticized for degrading water quality and for compromising the health of wild salmon populations.
Though spar cages contain adult fish more securely than salmon pens, escapes of juvenile fish and eggs from offshore farms could reduce the fitness of wild populations. And though the open ocean has the benefit of strong currents to dilute pollution, the amount of nitrogen produced by fish food and feces is still immense. “If the offshore industry grows as large as NOAA’s goal of $5 billion a year, its nitrogen wastes would be equivalent to that of the untreated sewage of 17 million people,” says Rebecca Goldburg, senior scientist with the conservation group Environmental Defense.
Because ocean carnivores are fed meal made in part from fish, farming them doesn’t necessarily alleviate pressure on wild populations. Two to five times more wild-caught fish are used in feeds than are harvested from aquaculture, according to a report that Goldburg published for the Ecological Society of America. Goldburg and other biologists are concerned that the new National Offshore Aquaculture Act does not adequately address any of these environmental issues.
Advocates of offshore farming recognize the challenges but argue they can be overcome. “My view is you have to look at the mistakes of the past and learn from them,” says Randy Cates, president of Cates International. “Can wild fisheries meet the increase in seafood demand?” he asks. “No. Nor is ocean farming going to solve the fisheries problem. It’s only going to be part of the solution.”