by Jennifer Kulier, Media & Communication Resources
 

In the greenhouses at Grayson Hill Farms, you'll find the requisite tubes, tanks, and trellises, along with hundreds of tomato plants weighed down by ripening fruit. But these greenhouses are unique. Lift the vine of a tomato plant and peek beneath the floor decking into the water—that's right, water—below, and you could see a fish staring back at you.

Grayson Hill Farms, near Eldorado, Ill., grows tomatoes using the hydroponic method, meaning that no soil, only nutrient-enriched water, is used. Beginning in 1999, using technology developed at SIUC and with the assistance of zoologist Chris Kohler, director of the SIUC Fisheries and Illinois Aquaculture Center, the farm began raising fish in the greenhouse water to make their operation more productive. The farm raises tilapia, a food fish from the Mideast and Africa that is tolerant of low-oxygen conditions and can be raised indoors year-round. The fish is mild-tasting and subtly sweet, comparable in flavor to bluegill.

The idea of raising tilapia in Eldorado may raise eyebrows now, but SIUC  fisheries scientists believe fish farming is primed to become a significant part of the region’s agricultural production, thanks to excellent water sources, a good climate, and proximity to major markets.

In fact, since 1950, when the SIUC fisheries program began, aquaculture has been part of its mission. Researchers have identified suitable fish species, developed spawning and rearing techniques, and formulated fish medications, all helping to lay the foundation for what aquaculture has become today—a $980 million U.S. industry raising fish for food, bait, and sport fish stocking.

SIUC researchers were the first to use cages in the culture of fish and to prove that it was possible to spawn catfish in captivity—thus contributing significantly to the development of the catfish farming industry. They pioneered the use of special filters that recycle the water in fish tanks by converting toxic ammonia from fish waste into nontoxic nitrate.

Some 25 years ago they did early work on hydroponics and aquaculture, which the Grayson Hill Farms project has built on. And in the 1990s, following successful safety tests at SIUC, the U.S. Food and Drug Administration approved the hormone human chorionic gonadotropin (hCG) for use in aquaculture. By inducing ovulation in female broodfish, hCG is necessary for the spawning in captivity of many species of fish.

Much of the Fisheries Center’s research has paved the way for the launch of the new aquaculture industry in Illinois.

Take the hybrid striped bass, for example. A cross between the striped bass and white bass, the hybrid is in demand worldwide for its firm fillet and good taste. Production is now concentrated in California and the Carolinas, but after 12 years of research to develop culturing techniques, Kohler and zoologist Robert Sheehan believe the fish is ideal for cultivation in southern Illinois. "It grows well in our climate, the fingerling [young fish] production is nearby in Arkansas, and the fish brokers in Chicago want it," Kohler says.

As part of that effort, graduate student Anita Kelly recently studied the cold tolerance of various crosses of striped bass and white bass. She found that for the hybrid to overwinter well, standard grain-based feed had to be enriched with omega-3 fatty acids (found in the hybrid’s natural diet of small fish). Those results have generated much interest among fisheries scientists.

"The Fisheries Center has also been a leader in developing techniques to spawn fish out of season, so that fish can be bred as needed," Kohler notes. To increase productivity, some larger fish farms are already using the methods developed here, which involve keeping a certain number of broodfish indoors and carefully manipulating temperature, light/dark periods, and other factors.

Kohler and his students are continuing to refine culturing and rearing techniques for different species and to evaluate species for their suitability for Midwest fish farming. They’re also currently working to develop cost-effective fish feeds that result in less solid waste, or waste that can more easily be mechanically removed from tanks (treating effluent is a major concern for fish farms).

But SIUC’s aquaculture efforts reach far beyond the Midwest. In the tropical rainforest of Peru, researchers are developing procedures that local residents can use to pond-raise pacu, a fruit-eating fish native to the Amazon. Their work includes research on spawning, nutrition requirements, and population density for economical production.

The pacu project is part of the Pond Dynamics Aquaculture Collaborative Research Support Program—a global, multi-university effort to enhance food production and sustainable economic growth in developing countries. In the Peruvian rainforest, one fish pond can mean the difference between a family that lives comfortably and one that struggles to put food on the table. And aquaculture can begin to change an economy that has been too dependent on slash-and-burn agricultural practices devastating to the forest.

Researchers like pacu because the species is tolerant of low-oxygen water and doesn't require a lot of expensive protein in its diet. Local residents like pacu too. The fish's mild flesh sometimes takes on a subtle flavor of the fruit it’s been eating. And since pacu can be raised year-round, with ponds productive for years, there's always some food and money coming in.

Back home, the Fisheries Center’s outreach efforts have helped jump-start the fish-farming industry in Illinois. With SIUC's Office of Economic and Regional Development, the center conducts workshops to teach farmers the basics of fish farming. For its part, the state has dedicated $12 million to build a fish processing plant in Pinckneyville and to fund the Illinois Fish Farmers Cooperative, a group charged with developing the industry.

It’s sink-or-swim time—and it looks like this endeavor will stay afloat.

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