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.
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