News: AAAS 2013 Annual Meeting News
Can Fish Farms Feed the World?
There’s nothing fishy about it: the world’s population has reached 7 billion and is projected to increase to 9 billion by 2050. The global food supply needs to expand dramatically.
Aquaculture—an industry that has experienced dynamic growth—could make a major contribution to the world’s protein needs, researchers said at the AAAS Annual Meeting. They were also candid about challenges ahead; namely, ensuring that fish-farming is sustainable as it is scaled up.
This means ensuring that aquaculture facilities don’t degrade the environment and that fish feed is high-quality and not in competition with human food sources. “This is particularly critical in light of issues around global food security,” said Jeff Silverstein, National Program Leader in Aquaculture at the USDA Agricultural Research Service.
Photo of several production systems at Bell Aquaculture. Courtesy of Bell Aquaculture.
Fish production is “by far the most efficient source of animal protein production today,” Silverstein said. Fin fish and shrimp, for example, require about one pound of feed to produce one pound of meat, compared to poultry, which requires two pounds, and pigs, which require three, according to Silverstein.
To meet the global seafood appetite, aquaculture will need to “integrate the many improvements being developed in separate sectors, like nutrition and fish-production systems,” Silverstein said.
One such improvement is the development of feed that is high quality, meeting all the nutritional needs of fish but excluding ingredients consumed by humans.
“In a world with an ever-growing population, how sustainable is it to continue feeding fish ingredients that humans need?” asked Margareth Overland, professor at the Norwegian University of Life Sciences. These ingredients include things like fish oil and plant-based products. “Fish feed of the future needs to be based primarily on non-food raw materials,” she said, “and I am studying some promising products.”
These include microbial organisms like yeast, which have the ability to convert low-value biomass (such as wood) into high-quality feed ingredients.
“What’s exciting here from a sustainability viewpoint,” said Overland “is that microbial ingredients not only can be produced from non-food raw materials, they also use very little water. From the production standpoint, they provide high-quality protein and other components that have health benefits.” Research shows that feed made from microbial ingredients supports fish growth and prevents intestinal inflammation, according to Overland.
“The conversion of non-food materials into high-quality feed resources could truly help make aquaculture sustainable,” she concluded.
Another important consideration is fish-farm expansion, which has been constrained in the past by limited water resources, site access and regulatory limitations.
At the Conservation Fund Freshwater Institute Shepherdstown, West Virginia, Steven Summerfelt and colleagues focus on increasing farmed fish production in systems that minimize water use. They have developed land-based, closed-containment systems that use water recirculation technologies. “This allows us to produce fish using a fraction of the water typically required on industrial fish farms,” he said.
But that’s not the only benefit. “Our systems also allow us to capture the nutrients in the waste of the fish, for re-use, and they serve as effective barriers for fish pathogens.” The absence of pathogens eliminates the need for vaccination and improves fish welfare, Summerfelt said.
What’s more, these systems are scalable. They can be located just about anywhere, reducing the need to ship and refrigerate the fish. Proving the viability of these systems, a trial of Atlantic salmon raised in West Virginia showed a survival rate of 97%.
“Right now, there are five land-based, closed-containment systems around the world, all showing good results,” said Summerfelt. “Twelve more are in the planning and construction stages. Their use could greatly expand domestic and global fish farming with minimal environmental degradation.”
Together, the solutions offered by these and other researchers show promise for sustainably increasing global fish production. “Integration of all these advances—that is what will be key,” Silverstein said.
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