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What are the pros and cons of marine aquaculture, of
raising ocean fish instead of catching them in the wild?
Marine aquaculture has grown in popularity in response to
dwindling supplies of wild fish in the world’s oceans. According to
the Pew Oceans Commission, a blue-ribbon panel of fisheries and
marine-biology experts, high-tech fishing practices such as drift netting
have led to a potentially irreversible decline in the populations of key
seafood species. Some shark, tuna, and cod species have declined by as much
as 90 percent in the past few decades. Most marine biologists agree that, as the human
population continues to grow worldwide, there will not be enough
wild-captured fish to meet the demand for seafood. Aquaculture, “the
propagation and rearing of aquatic organisms in controlled or selected
environments,” as defined by the U.S. National Oceanic and
Atmospheric Administration, is seen by many as the best way to fill the
gap. Currently aquaculture supplies about 30 percent of the world’s
seafood, up from just 4 percent three decades ago. But aquaculture’s downsides give many scientists
pause. Studies indicate that, despite the promise of reducing pressures on
wild fish, aquaculture requires 2 pounds of wild-caught fish to use as feed
to make 1 pound of farmed fish. Another concern: Breeding farms facilitate
the spread of diseases that can contaminate wild fish populations. To control such outbreaks, many fish farmers treat
their stocks with antibiotics, which can also make their way into the
oceans and wreak havoc. The farmed fish themselves also escape from their
pens and interbreed with and take over habitat traditionally occupied by
wild populations. Another major problem with aquaculture is its destruction
of natural habitats. Shrimp farming, for example, is contributing to the
destruction of coastal mangrove forests in the Philippines, Thailand, and
elsewhere. But many scientists do feel that aquaculture has the
potential to help the world’s marine ecosystems rebound — if it
is done conscientiously. According to the Monterey Bay Aquarium’s
“Seafood Watch” program, the greatest power to end
irresponsible aquaculture rests with consumers. The California
organization’s Web site offers tips on which kinds of farmed seafood
to buy and which to avoid. Although no one person’s choices will
improve the environment dramatically, consumers can play a role in how
producers treat the ecosystems they use.
For more information: NOAA,
www.nmfs.noaa.gov/mediacenter/aquaculture/; SeaWeb’s “Ocean
Briefings: Marine Aquaculture,”
www.seaweb.org/resources/briefings/aquaculture.php; Monterey Bay
Aquarium’s Seafood Watch Regional Seafood Guides,
www.mbayaq.org/cr/SeafoodWatch/ web/sfw_regional.aspx.
Send questions to Earth Talk, care of E/The Environmental Magazine,
P.O. Box 5098, Westport, CT 06881 or e-mail earthtalk@emagazine.com.
This article appears in Feb 1-7, 2007.
