What are the pros and cons of marine aquaculture, of raising ocean fish instead of catching them in the wild?

What are the pros and cons of marine aquaculture, of raising ocean fish instead of catching them in the wild?

—Jeanne L., Norwalk, CT

Marine aquaculture, an age-old practice in parts of Asia, has grown in popularity in western countries in recent years 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 populations of key seafood species. Some shark, tuna and cod species have declined as much as 90 percent in the past few decades.

Most marine biologists agree that, as human population continues to grow worldwide, there will not be enough wild-captured fish to meet demands 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 (NOAA), 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 four percent 30 years ago.

James McVey of NOAA’s Sea Grant program says aquaculture can reduce the need for seafood imports and provide jobs for coastal communities. “The U.S. currently brings in $10 billion in seafood from other countries,” he says. “With increased production capacity, our higher yields from aquaculture will bring down this trade deficit, and improve food security—where we’re not as reliant on other nations for food.”

But aquaculture’s down sides give many scientists pause. Studies indicate that, despite the promise of reducing pressures on wild fish, aquaculture requires two pounds of wild-caught fish to use as feed to make one pound of farmed fish. Further, says SeaWeb, breeding farms—where thousands of fish, and their waste, are concentrated—breed diseases that can then escape and contaminate wild fish populations.

To control such outbreaks, many fish farmers treat their stocks with antibiotics that 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, according to SeaWeb, is its destruction of natural habitats. The group blames shrimp farming, for example, for destroying coastal mangrove forests in the Philippines, Thailand and elsewhere.

But many scientists do feel that aquaculture has the potential for helping the world’s marine ecosystems rebound—if it is done conscientiously. Among other things, SeaWeb recommends that fish farmers avoid using drugs to fight disease and that governments do more to regulate and police aquaculture operations to make sure otherwise pristine waters are not fouled and sensitive coastal ecosystems are not damaged.

According to the Monterey Bay Aquarium’s “Seafood Watch” program, the greatest power to end irresponsible aquaculture rests with consumers. The organization’s website offers tips on which kinds of farmed seafood to buy and which to avoid. While no one person’s choices will improve the environment dramatically, collectively consumers can play a role in how producers treat the ecosystems they utilize.

CONTACTS: NOAA; SeaWeb”s: Marine Aquaculture; Monterey Bay Aquarium’s Seafood Watch Regional Seafood Guides