Tossing Mullet

By: George Crozier (columnist) – Lagniappe Mobile

Aquaculture rises globally

“Shrimp boats is a’comin” – Not so much!

     Only really old people will recognize the 1951 pop song but it popped into my head with the renewed discussions locally concerning the potential for fish farms being developed along the Gulf Coast.
Wild harvest production of seafood in this country is a very small percentage of the seafood that we consume as a nation because 80 percent or so of all seafood consumed here is imported from overseas.
     Of that, the vast majority is, in fact, farm-raised. This is particularly true of salmon and shrimp, seen as delicacies, and tilapia, the most mundane and practical of the trio.
     There is great irony in the fact that Auburn University has taught much of the world how to grow fish in farms. This grew from the early Aid to International Development programs and in some ways fostered the growth and success of the spectacular Department of Fisheries and Allied Aquaculture at the University. This started with catfish farming, and we still produce most of the catfish that we eat, but competition from Viet Nam has become a contentious issue of late. The Auburn programs have since been duplicated at other land grant universities and the result is the dramatic success of aquaculture and its oceanic counterpart, mariculture. To Read More…

What Lies Below

     While most people are attracted to the Lake Martin area by its natural beauty and recreational opportunities, some are drawn from across the country and even from overseas to the Tallapoosa River watershed because it is among the most biologically diverse regions of the United States.
     In fact, Alabama is home to more different species of fish, crayfish, mussels and snails than any other state in the union. To Read More…

High-Intensity Raceway Production Could Put Catfish Producers in the Fast Lane

YSI Environmental

     An experimental, high-intensity raceway production system designed by researchers at Auburn University could drive Alabama producers’ catfish production costs – currently well above 70 cents per pound – down to about 50 cents by improving feed and energy efficiency.
     Carefully managing fish in tightly populated raceways could yield 25,000 to 35,000 pounds of catfish per acre per year, more than three times the state’s average of 8,000 pounds per acre per annum.
     “The main goal of the system is to produce a high volume of fish in a small area with minimal energy input and lower production costs than traditional methods,” says graduate research assistant Travis Brown, who is managing the project as part of his dissertation through Auburn’s Department of Fisheries and Allied Aquacultures. Though converting a traditional earthen pond to a raceway system may cost as much as $7,000 to $8,000 per acre, Brown says the reduction in input costs associated with increased production, as well as the tripling of production are likely to< pay off quickly.
     Butch Wilson, president of the Alabama Catfish Producers Association and the producer hosting the research project on his 450-acre (182-hectare) farm near Marion Junction, Ala., says his industry’s future depends upon cutting per-pound production costs and boosting output. “If we’re going to compete in a world market, it’s critical,” he says.

Tight Fit

     The high-volume system packs an acre’s worth of fish into each of six concrete raceways that are 32 feet long, 16 feet wide and 4 feet deep (9.75 meters by 4.9 meters by 1.2 meters). The raceways are arrayed side-by-side in a portion of a traditional, 6-acre (2.4-hectare) earthen pond.
     The series of raceways comprises a multi-stage system. Though they contain fish of a uniform size and age – minimizing predation – each is stocked at different times throughout the year to stagger harvest dates and prevent the pond from carrying a full load of harvestweight fish in each raceway at one time.
     In addition to concentrating fish in the raceways, the system concentrates aeration efforts where the fish are located, notes Brown. Instead of running conventional paddlewheel aerators that require three to five horsepower per acre, the Auburn system requires just 0.5 horsepower per raceway to operate a slow-turning paddle wheel.
     “Our paddles are just for current flow, not for aeration,” Brown says. “We have a large paddle
running at 1.2 rpm to create a constant current through the raceway, counterclockwise around the pond. We can evacuate the water from the raceway every three minutes, and we’re trying to keep the entire quantity of water thoroughly mixed to prevent stratification during the summer months.”
     An air diffuser system located at the head of each channel is operated by 1.5 horsepower, low-pressure blowers activated intermittently by the system’s water quality monitoring instruments to provide supplemental oxygen in each raceway as needed.
     As the water travels away from the raceways and out into the rest of the pond, it encounters an array of biological treatments – a menagerie of aquatic species that keep it aerated and clean. A stable
bloom of algae thrives on dissolved nutrients from manure and bits of feed, adding oxygen to the water. However, notes Brown, pumping solid manure out of a trough at the end of the raceways minimizes nutrient overloading that can cause boom-and-bust algal blooms. Brown says a bloom heavy enough to consistently maintain 20 to 30 cm of Secchi disk visibility represents the ideal level of algae to manage the system’s water.
     Beneath the surface, paddlefish graze on zooplankton. Tilapia control blue-green algae that can cause off-flavors in the catfish. Fathead minnows eat the flatworms that can cause proliferate gill disease, or “hamburger gill.” And red-eared sunfish or “shell crackers” keep mollusks under control.

Boosting Feed Efficiency

     Keeping fish in a raceway also makes it easier to deliver food to them quickly, efficiently and frequently, notes Prof. Jesse Chappell, who heads up the study. “We’re not trying to feed the same way other growers are feeding,” he says. “We’re feeding multiple times per day, getting feed efficiency in line with what the animal will do. We try to reduce stress and get the animal in the best possible position to obtain the best possible feed efficiency.”
     Chappell points out that most Alabama catfish farmers achieve feed conversion ratios (FCR) in the range of 2.8:1 to 3.0:1. His goal through intensive feeding is to improve FCR to 1.5:1. With today’s
feed costs nearly double what they were in early 2007, improving feed efficiency has a profound impact on the producer’s bottom line.
     In any fish production system, a significant proportion of the nutrient inputs end up as waste. Brown points out that collecting waste solids in a trough at the end of the raceways will allow high-intensity producers to recapture some of their feed investment.
     “Only 30 to 35 percent of the nutrients in the feed are utilized in fish growth and maintenance,” he explains. “If we can reclaim some of that money by using the fish waste in a slurry on farmland or as
compost, we have made this even more profitable.”

A Closer Watch

     Intensifying production requires more careful scrutiny of conditions in the raceways. To keep a close watch on temperature and dissolved oxygen levels, Brown and Chappell placed a YSI 5200 multiparameter monitoring and control instrument at the tail end of each raceway, and a seventh 5200 monitors the quality of incoming water. If oxygen or temperature drift outside of acceptable levels, the instruments call Brown’s cell phone with an alarm message. A low-oxygen reading will also activate an emergency blower system as necessary.
     Brown points out that he can also set the instruments to automatically dispense feed in each raceway. YSI software can automatically adjust feed timing and quantity based on biomass in the pond. He says he plans to bring the automatic feeding capabilities online soon. In the meantime, the YSI 5200s keep constant watch on water quality. “The more intensive the operation, the better management and control you need to have,” says Tim Grooms, Global Business Development Manager for YSI. “If you push the envelope too far, you can create a lot of stress.”
     Surprisingly, Wilson – whose Dean Wilson Catfish Farm encompasses 34 ponds – points out that the raceway system was actually his most stable pond during a power failure this summer.
     “We had a six-hour outage, which was very rare,” he recalls. “All we did in that pond was stick in a tractor with a portable aerator. That pond never got close to killing fish. In our other ponds, we were
running around, putting in aerators to keep fish alive.” A backup generator now provides peace of mind, he adds.
     Seeing the raceway system succeed on his farm provides another kind of peace of mind for Wilson – hope that his state’s catfish industry, battered for years by high production costs and competition from imports, can prevail through more intensive management.


For additional aquaculture information including specifications on YSI instruments, please visit: or

Ag Roundup!

     Ag Heritage Park will be the scene of a super-sized tailgate party Saturday,Nov. 8, from 9 a.m. to noon as the Auburn Universiry College of Agriculture, the AU Agricultural Alumni Association and a first-ever corporate sponsor farm-equipment giant John Deere-team up to host the 29th annual Taste of Alabama and Fall Ag Roundup. 
     The event has, become an Auburn homecoming day tradition, annually drawing 1,500 to 2,000 Tiger fans who have learned that for a mere $5 admission fee for individuals 6 and up, they can get their fill of a bounty of food items grown and/or processed in Alabama-from fried chicken strips, grilled goat sausage and farm-raised shrimp to boiled peanuts, Satsuma oranges and collard greens. A major hit last year was homemade peach and blackberry ice creams, made with peaches and berries produced at the Chilton Research and Extension Center in Clanton.
     In addition to food, Ag Roundup offers musical entertainment; visits from Aubie and the Auburn cheerleaders; exhibits from academic departments, student organizations and commodity or agribusiness groups; and loads of children’s activities. There also will be live and silent auctions offering dozens of top-quality goods to the highest bidders. Proceeds from the auctions go to fund scholarships for deserving students in the College of Agriculture.
     John Deere, as corporate sponsor, is also donating $10,000 to fund scholarships in the College of Ag.
     Ag Heritage Park is located on Samford Avenue, just across from the AU Athletic Complex and only tWO blocks from Jordan-Hare Stadium. For the homecoming game, Auburn will take on University of Tennessee Martin. Kickoff is set for 1:30 p.m.
     For more information on this year’s Taste of Alabama and Ag Roundup, contact Elaine Rollo at 334-844-3204 or

Troy Farmer Academic Achievements

     Troy Farmer, who holds a bachelor’s degree in fisheries management from Auburn and will be awarded his master’s in fish ecology in December, was one of 10 fisheries graduate students nationwide to be awarded the American Fisheries Society’s 2008 Skinner Memorial Award. That honor carries with it a cash award that winners use to attend the society’s annual meeting. At the 2008 meeting, held in Ottawa, Canada, in August, Farmer presented his master’s research and was selected to be part of the “Best Student Paper Symposium,” which included the top 16 student presesntations at the meeting. His master’s research focused on the dynamics of mercury bioaccumulation in largemouth bass and Southern flounder in Alabama’s Mobile-Tensaw River Delta. His co-advisors were fisheries professors Dennis DeVries and Rusty Wright. Though Farmer officially won’t receive his M.S. until December, he already has completed his master’s work and moved to Columbus, Ohio, to begin his Ph.D. studies in evolutio, ecology and organismal biology at Ohio State. His career goal is to become a fisheries reseacher at either the federal level or a research university.

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