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Auburn University Charts Path for 21st-Century Vision of U.S. Aquaculture

AUBURN, AL – Auburn University's Aquaponics Working Group has a new vision for U.S. aquaculture, one that includes far more predictability and efficiency than today's timeworn models of commercial fish production.

"Need is the mother of invention, and that's what is driving much of this research," says Dr. Jesse Chappell, group member and associate professor and extension specialist in the College of Agriculture's School of Fisheries, Aquaculture and Aquatic Sciences. "We've put together a multidisciplinary team from across campus to cover every aspect of a multi-trophic system of aquaculture production.”

The Aquaponics Working Group recently received the President's Outstanding Collaborative Units Award at Auburn. In addition to Chappell, members of the team include School of Fisheries, Aquaculture and Aquatic Sciences Professor Terry Hanson; Department of Poultry Science Professor Tung-shi Huang; Department of Horticulture Assistant Professor Daniel Wells; Department of Biosystems Engineering Assistant Professor David Blersch; and Glenn Loughridge, director of Campus Dining.

Multi-trophic aquaculture is the process of re-tasking production byproducts such as nitrogen waste (nitrate) from a fed aquatic species (catfish or tilapia) to fertilize plants or to feed another aquatic (plant) species. Fish waste naturally produces high concentrations of nitrogen that can be used to fertilize a variety of plants. This approach helps to conserve nutrient resource inputs in feeding fish while still yielding maximum farming returns over a limited acreage.

"When we make an investment in feed nutrients, we can pass it through farm animals and add value to it," Chappell says. "Fish are very efficient animals, but even they keep only about 25 percent of the feed they take in, turning it into fish biomass. They excrete the remainder of the nutrients in some form or another.

"That nutrient investment has value in whatever form we can capture. If we throw it away, we are literally throwing money away, and then we have to pay an environmental price."

The U.S. aquaculture industry is in the same place the poultry and swine industries were more than 60 years ago, Chappell says, so change has been a long time coming.

"Fish are tracking the same paths and for exactly the same economic drivers as these other animal protein production enterprises—gaining the predictability and the high level of survivorship and efficiency that this type of system can give us," he said.
Methods are available today that allow for the almost full utilization of the nutrient investments made in aquaculture, Chappell says.

"We want to capture those valuable nutrients that we've purchased, pass them through the fish and then recapture the nutrients and water as we pass them through a variety of plants to turn it in some kind of marketable form," he says. "That's what this advanced system is all about."

Auburn's multi-trophic project actually began about 12 years ago with one greenhouse equipped with a fish production system and an adjacent greenhouse equipped for plant production, Chappell says.

"It's important that the greenhouses be decoupled—that is, not occupying the same space—because if we have plants in the fish house, they would always be moist, creating an environment for increased disease pressure and incidence of plant losses," he says.
The two production platforms are hydraulically connected through the water system.

"We feed the fish, and they absorb as much of the feed nutrients as possible, transforming our feed investment into fish biomass," he says. "They retain and excrete the balance."

This system is designed in such a way that it's not producing or exporting manure, Chappell says.
"We are processing the waste solids within a part of the fish production system so we don't bring solids over to the plant house," he said. "We're bringing over warm water enriched with a good concentration of nitrates, which is what the plants need. We can vary those nitrates from as low as 50 parts per million up to 300 parts per million, depending on how much particular plants need and how much water or nutrients we're using on a day-to-day basis."

In the last two to three years, researchers have partnered with Campus Dining Services, Chappell says, to offer students high-quality foods produced on campus.

The original greenhouses have been refurbished, and two additional greenhouses are being built to produce even more seasonal vegetables for student dining facilities.

Some 250 to 350 pounds of live fish (tilapia) per week are dressed and made available for use in the campus kitchens. Hundreds of water, tilapia, cucumber, and tomato samples have tested free of pathogens and safe for human consumption.

Commercially, Chappell envisions a 2,000- to 3,000-acre tract of land with a feed mill as its central hub, providing the feed necessary for an array of fish production barns. "We don't need any trucks delivering feed with this system, and we can engineer production systems that make the fish literally swim to the processing plant door. We can do all of this within a quarter-mile of the feed mill."

This concept, Chappell says, makes economic sense because so many cost points can be eliminated. Everything can be done on one tract of land to fully capture and re-task the investment made in nutrients, water and energy. "Using an Auburn-developed technology, we'd take the slaughter plant waste and turn it into fish meal, with no odor nor wastewater," he says. "It's a flash-drying technology that turns discarded processing waste into dry meal in about two minutes. We can sell or use that fish meal. It's currently selling for $1,700 to $1,800 per ton for the quality meal this technology provides."

The water recovery element will reprocess the water from fish systems, taking the manure out of the water and digesting it to form methane or bio-gas to provide energy to help operate the machinery in the feed mill or processing plant.

Current fish production systems are monocultures, and producers spend a lot of money dealing with waste load, Chappell says.

"We can offset the cost completely and often earn more on plant biomass than on fish," he said. "In traditional aquaculture, we fill ponds, but we don't pass water through ponds. We need a fair amount of water to operate our ponds, but the controlled environment system we envision reduces water use by more than half." In the end, Chappell says, it's all about good business.

"When we invest in feed, we want to capture all of the value that's possible," he says. "Good-quality catfish feed today will cost $400-plus per ton, and higher-quality fish feed costs closer to $600 per ton. We need to do all we possibly can to turn that feed into high survivorship for our fish and better profitability to return revenue to the investment."

Catfish are currently being produced in west Alabama for 85-92 cents per pound, and producers are selling them for 90-95 cents per pound.

"If you're buying fish for $1 per pound, when you cut filets, you throw away about two-thirds of that fish's body, unless you process it into fish meal," he says. "Automatically, that meat cost is $3 per pound before you turn the processing plant's lights on. It's a product that costs more than chicken or pork or, sometimes, steak. "What if that price to the grower is 70 cents, and he has a 15-cent margin in it? He likes it better, and the consumer likes it better. We can catch the byproducts and turn them into other merchantable forms."

A good pond manager with catfish or tilapia in Alabama might produce 10,000 pounds of fish per acre, but a very crude multi-trophic system routinely produces 350,000 to more than 1 million pounds of live fish per acre, depending on the type system used, Chappell says. "In the U.S., our per-capita consumption of seafood is about 15.5 pounds. The remainder of the developed world is at least 30 pounds. Why are we lagging? We want to work on changing that and improving the quality of peoples' diets and health."

If the quality of seafood products is high, consumers will find them much more acceptable than some of the fast-food dietary trends of today, Chappell says.

Auburn's aquaponics research has attracted more than $1 million thus far in competitive grants, Auburn's Hanson says. "Producers ultimately want to know if they can make money," the aquacultural economist says. "They need to know if they can get a return on their investment and make a profit, and that's part of the work we're doing."

Hanson has worked with several aquaponics projects, with the most successful being those that find a niche market.

"Family operations also do well because labor costs are not charged as a cash account," he says.

The vision of Hanson and other researchers is that U.S. consumers will eat more fish when it comes from commercialized aquaponics technology.

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