A Seafood Paradox: Will Fish Farming Save Or Deplete Our Ocean Fisheries?

``A lot of countries could use more protein, and aquaculture is a good way to get there,`` says Rosamond Naylor, an economist at the Stanford Institute for International Studies.

The problem, Naylor points out, is that farmed salmon, shrimp and other carnivorous species often take more out of the oceans than they keep in. That`s because certain farmed fish are given processed feed made from wild catches of herring, mackerel, sardine and other ocean varieties. Naylor estimates that nearly two pounds of wild fish are required for every pound of farmed fish raised on processed meal.

On balance, aquaculture still adds to the world`s supply of seafood, she says. Yet fish farming influences wild populations - displacing natural breeding habitats, spreading disease and polluting the oceans in many ways that haven`t been measured.

Naylor and other researchers from around the world will discuss the costs and benefits of fish farming at a symposium on aquaculture to be held on Sunday, Feb. 18, at 3 p.m. PT at the annual meeting of the American Association for the Advancement of Science (AAAS) in San Francisco.

Speakers at the session organized by Naylor will describe some of the negative environmental, economic and social consequences of aquaculture, and will outline specific solutions to counter those impacts.

Commercial fish farms are expanding rapidly, especially in Asia, taking up thousands of square miles of coastal land. Panelist Jason Clay of the World Wildlife Fund will explain how shrimp farms often replace wetlands and mangroves that serve as nurseries for native fish populations.

Nils Kautsky from the University of Stockholm in Sweden will show how a farm can affect surrounding areas by discarding excess fishmeal, transferring parasites to wild populations and introducing exotic fish into native ecosystems. Kautsky will demonstrate how the ``footprint`` of a farm - its influence on the local environment - can be up to 50,000 times larger than the physical farm itself.