Next-Generation Fish-Farming Techniques Aim For Sustainability
Posted by Unknown in Fish Farming, Sustainable Agriculture on Friday, 15 March 2013
BY Roxanne Palmer
IBTimes
By
midcentury, mankind must double food production to fill the bellies of
an exploding population of humans, according to the United Nations. A
big part of that growth is likely to come from farmed seafood.
“With Earth’s
burgeoning human population to feed, we must turn to the sea with new
understanding and new technology,” famed oceanographer Jacques Cousteau
said in 1973. “We need to farm it as we farm the land.”
Balancing
accelerated food production with sustainability is a tricky act, but on
Sunday scientists at the American Association for the Advancement of
Science annual meeting in Boston described how aquaculture could
possibly pull it off -- and what challenges lie on the road ahead.
U.S. Department
of Agriculture, or USDA, aquaculture program leader Jeffrey Silverstein
pointed out that 70 percent of the Earth is covered in water, yet only
1.5 percent of human food is drawn from it.
Finned fish are
much more efficient sources of protein than other kinds of livestock --
for every pound of food you put into a fish, you get about a pound of
body weight. In contrast, you have to feed chickens two pounds of food
to get a pound of body weight, and you have to give pigs three or four
pounds of food for each pound they put on, according to Silverstein.
However, that
pound of fish food can require several pounds of flesh to produce, much
of it from other fish, usually from processed pelagic fish such as
anchovies. To increase sustainability, fish farmers have been turning to
diets that consist of more and more plant products and less and less
fish meal.
But using plant
products brings its own host of problems, one of the more significant
being that a farmed fish that dines more on plants than on animals tends
to be less oily and nutritious. Frequently, farmed fish have to be fed
fish oil near the end of their lives to help make them healthier for
humans to eat. One of the ways to mitigate that dip in nutrition could
be to turn to an alternative source of fish food: microbes.
Researchers are
currently trying to perfect the production of various microbes that
could bulk up a farmed fish’s diet, thereby cutting the amount of food
and agricultural land used indirectly by fish food production.
Margareth
Overland, a nutritionist with the Aquaculture Protein Center at the
Norwegian University of Life Sciences, said one of the more promising
microbial sources for fish food is yeast grown on processed spruce wood.
Algae and bacteria are also being studied.
Microbial and
bacterial diets not only pump a fish full of vitamins, but also seem to
help reduce the intestinal inflammation in the fish.
“Not all that different from the probiotic yogurts we buy in stores,” Overland said.
However,
microbe-based food is years away from being ready to supply large
industries, and researchers still need to conduct taste tests to make
sure there's nothing especially fishy about a salmon that's been dining
on yeast.
Changing fish
food will likely also help cut the carbon footprint of many fish farms.
One of the biggest components of a Norwegian salmon farm's
greenhouse-gas impact is associated with the transportation of food
sources, so if microbial food is a success, it could lessen that impact.
Other options
for alternative fish food exist, too. A British business magnate has
been creating protein meal made from housefly larvae, better known as
maggots, and selling that to poultry and salmon farms in South Africa,
as NPR reported.
There may also
be ways to tweak fish to get more nutrition from them. Preliminary
research has identified a genetic variant in rainbow trout that prompts
them to make more omega-3 oils, a trait that could be exploited through
traditional breeding techniques, USDA's Silverstein said.
At the moment, “genetically improved” fish stocks make up just 10 percent of farmed fish in the U.S., Silverstein said.
That figure
could change soon. In December, the U.S. Food and Drug Administration
released a preliminary finding that AquAdvantage salmon -- a genetically
modified Atlantic salmon that grows to full size much faster than
normal fish thanks to the addition of genes from Chinook salmon and the
ocean pout -- would have “no significant impact” on the environment.
That move signals that AquAdvantage salmon is nearing final approval.
But
AquAdvantage salmon has become a major flashpoint in the debate over
genetically modified organisms. Last week, the FDA said it would extend
the comment period on its environmental assessment of AquAdvantage
salmon until late April.
Improvements in fish-farm construction are also expected to boost aquaculture production.
Catfish farmers
have found success with split-pond designs. Such a design entails
separating a smaller area, where the fish are kept, from a much larger
area, where the water is treated. Split-pond farming has helped catfish
farmers see their yields triple to 15,000 pounds per acre from 5,000
pounds per acre in the last several years, according to Silverstein.
Land-based
enclosures are also catching on in aquaculture. Right now, you might be
perturbed at the thought of a salmon grown in the Midwest, but such a
scenario could be in the future of sustainable fish farming.
Steven
Summerfelt, who oversees research into sustainable aquaculture
techniques at the Arlington, Va.-based nonprofit environmental group The
Conservation Fund, said the latest contained fish farms use less water
and pollute far less than farms in open oceans.
“If done properly, there’s no discharge allowed,” Summerfelt said.
A single
3,300-metric ton next-generation salmon farm could produce enough fish
each week to fill up an entire schoolbus, top to bottom, side to side,
Summerfelt said -- a rate that could satisfy 1 percent of U.S. salmon
consumption.
Human
population explosion and declining wild-fish stocks around the globe
practically dictate that fish farming will be a necessity in the near
future -- and if the next generation of aquaculture realizes its
promise, it could ensure that seafood stays on the plate for generations
to come.
