While Americans' appetite for seafood continues to grow, most of us know little about where our fish comes from or how it was produced. In California, more than half of our seafood comes from aquaculture, often imported from fish farms in other countries. Just as most chickens, pigs and cows are raised in tightly confined, intensive operations, so too are many farm-raised fish.

But raising fish in tight quarters carries some serious risks. Disease and parasites can be transmitted from farmed to wild fish. Effluents, antibiotics and other chemicals can be discharged into surrounding waters. Nonnative farmed fish can escape into wild fish habitat. And a reliance on wild-caught fish in aquaculture feed can deplete food supplies for other marine life.

These environmental impacts have been evident in many other countries with intensive marine fish farming. In Chile, where industry expansion was prioritized over environmental protection, salmon aquaculture has collapsed, causing a major blow to what had been one of Chile's leading exports. Tens of thousands of people are now jobless in southern Chile, where the salmon farming industry once boomed.

If aquaculture is to play a responsible role in the future of seafood here at home, we must ensure that the "blue revolution" in ocean fish farming does not cause harm to the oceans and the marine life they support.

In December, Rep. Lois Capps (D-Santa Barbara) introduced in the House the National Sustainable Offshore Aquaculture Act, a bill that addresses the potential threats of poorly regulated fish farming in U.S. ocean waters. Her bill shares many of the features of a California state law, the Sustainable Oceans Act, which was written by state Sen. Joe Simitian (D-Palo Alto) and signed by Gov. Arnold Schwarzenegger in 2006. That legislation regulates fish farming in state waters, which extend three miles off the California coast. At present, all aquaculture operations in California and the U.S. are located just a few miles offshore.

If the U.S. and other states follow California's lead, we may be able to reward innovation and responsibility in aquaculture and at the same time prevent the kind of boom-and-bust development that happened in Chile. Unlike previous attempts to legislate fish farming at the national level, the Capps bill would ensure that U.S. aquaculture in federal waters, which extend from three to 200 miles offshore, establishes as a priority the protection of wild fish and functional ecosystems. It would ensure that industry expansion occurs only under the oversight of strong, performance-based environmental, socioeconomic and liability standards.

The bill also would preempt ecologically risky, piecemeal regulation of ocean fish farming in different regions of the U.S. Indeed, regulation efforts are already underway in many states, with no consistent standards to govern the industry's environmental or social performance. If these piecemeal regional initiatives move forward, it will get much more difficult to create a sustainable national policy for open-ocean aquaculture.

Previous federal bills introduced in 2005 and 2007 were fundamentally flawed -- and ultimately did not pass -- because they put the goal of aquaculture expansion far above that of environmental protection. Now, for the first time, a bill has been introduced that would demonstrably protect marine ecosystems, fishing communities and seafood consumers from the risks of poorly regulated open-ocean aquaculture.

The Obama administration is currently developing a national policy to guide the development of U.S. aquaculture. The administration would do well to embrace the vision articulated by Capps and Simitian for a science-based and precautionary approach to help ensure a responsible future for U.S. ocean fish farming.

Rosamond L. Naylor is director of the program on food security and the environment at Stanford University. George H. Leonard is director of the aquaculture program at the Ocean Conservancy in Santa Cruz.

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