Marine researchers at the University of California, Santa Barbara, mapped out the potential of the open ocean to support farmed fish and came to some surprising conclusions.
August 21, 2017 — About five out of every six fisheries worldwide has reached or passed the limit of what it can sustainably produce, according to the World Wildlife Fund. Drought, dams, agricultural runoff and other pressures have depleted wild salmon populations in the Eastern Pacific, while on the east coast of North America, wild Atlantic salmon exists mainly in the memories of the Greatest Generation. Bluefin tuna, the preferred delicacy of the world’s finest sushi chefs, is at 2.7 percent of its historical population – about the same as the Bengal tiger.
Meanwhile, seafood farmed in coastal regions has been infected with sea lice, pollutes neighboring ecosystems with waste, sometimes produces fewer nutrients than are fed into the system, often destroys carbon-sequestering mangroves and can require large amounts of antibiotics to stave off disease.
But according to a new study from the University of California, Santa Barbara’s Bren School of Environmental Science and Management, aquaculture could feed a global population expected to grow to nearly 10 billion by 2050. Lead author Rebecca Gentry, a newly minted PhD in marine ecology, and her colleagues wrote that the open ocean “is largely untapped as a farming resource,” representing “an immense opportunity for food production.” In the study published August 14 in the journal Nature Ecology & Evolution, they found that the entire world’s current output of wild-caught seafood could be farmed in areas that in total would comprise just 0.015 percent of the ocean’s surface area, if grouped together in a way that the authors note would not be realistic or recommended. That’s the equivalent to the size of Lake Michigan.
“People assume the oceans are big but no one had quantified it,” Gentry said. “There’s not that much broad-scale ecological research on marine aquaculture, so we needed a base of information to get an idea of where we can do it.”