Over the next 30 years, global aquacultural production could reach 60-120 million metric tons, putting it in the same league with livestock enterprises like poultry and swine. And as a market for soybeans, aquaculture is potentially large and relatively untapped, says Paul Brown, a Purdue University aquacultural nutritionist.

“Two years ago, a graduate student and I looked through all the literature and found 17 aquaculture species that had some form of soy in their diets,” Brown says. “A similar survey this year showed 54 species that had soy as a part of their feed. That's a significant increase, but still represents a small part of aquaculture.”

As Brown notes, 358 species are known to be cultured in ponds, paddies, tanks or cages. For every species now utilizing soy, there are about seven that don't appear to be. Many of those untapped species, Brown suspects, are potential markets for soy-based feed, and new types of fish are being brought into commercial production every year.

For U.S. soybean farmers, the most evident example of this type of utilization is in catfish farming. The industry — which is concentrated in the Midsouth — produces 700,000 tons of catfish feed a year, and about 40% of that content is soymeal.

To make that much meal, you need about 12 million bushels of beans, estimates Bob Harris, a veteran livestock feed producer who oversees Fishbelt Feeds, Inc., in Moorhead, MS. That's equal to the soybean production of Oklahoma and Texas in 2000. Or, to put it another way, about every fifth row of soybeans grown in Wisconsin.

Compared to the total U.S. crop of 2.77 billion bushels, 12 million bushels moving into catfish production seems insignificant. But it's a market that hardly existed at all 20 years ago.

U.S. catfish production went from 200 million pounds in the 1980s to about 600 million pounds this year. In the early 1980s, soybeans didn't account for a high percentage of feed content, either. In that period, much of the protein in catfish rations came from fishmeal.

But as demand grew for catfish, the industry had to turn to other protein sources, and soymeal became a safe choice, says Harris.

“Global supplies (of fishmeal) can't keep up with the projected demand, either,” says Purdue's Brown. “Demand from aquaculture simply dwarfs the supply of fishmeal and increases its cost. Where producers can shift to soymeal, they save money now.”

The growth of the U.S. catfish industry reflects a worldwide change in the importance of aquaculture. While fish have been grown in ponds for thousands of years, most aquaculture was localized and mainly part of a subsistence system. But in the 1980s, the demand for fish and other aquatic species outstripped the sustainable capacity of the world's oceans and freshwater resources.

“We are experiencing steady increases in world population and increasing per capita consumption of fish and shellfish,” Brown observes. “This is probably the last major food item we still predominantly hunt and gather from wild populations, and there are no projections for increased harvests.

“In the last 20 years in North America, we have examples of commercial fish populations that have been declared rare and endangered on every coast of North America,” he notes.

Approximately 82% of the aquatic resources available to U.S. fishermen, in fact, are either over-harvested, at maximum harvest or the status of the stock is unknown, he adds.

Where natural stocks declined for high-demand species, aquaculture is filling the gap. One example of the shift from wild fish to commercial production is the striped bass. Populations declined from 1970 to 1990 to the point that the fish was declared endangered. It's only been in the last couple of years that stocks rebounded for limited commercial harvest.

“However, as striped bass supplies declined, the culture of the hybrid striped bass increased, helping to meet demand,” says Brown. “We've seen similar examples of a shift to aquaculture with species like red drum on the Gulf Coast and salmon on the West Coast.”

Demand for fish will increase partly because of population trends. Over the next 40 years, the global head count will increase from 6 billion to 10 billion. In many developing countries where populations will grow the most, fish already is a dietary staple. Consumption also is increasing in the industrialized world because of perceived health benefits.

Grower-funded programs already have played a role in bringing soybeans into aquaculture. As early as the mid-1980s, the American Soybean Association was funding studies and presentations on the use of soymeal in fish food.

“It's going to take a pretty broad initiative to fully tap the potential of aquaculture,” Brown explains. “Unlike pork, where you're dealing with one basic animal, there are hundreds of commercial fish species, and each will require its own set of studies to determine the exact economic fit for soybeans.”