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Fish grader boon to catfish farmers

Technology is giving a helping hand to catfish producers conforming to a shift in market demand. Paul Dees, chief operating officer, Dillard and Company, Inc., near Leland, Miss., is one of a growing number of Delta catfish producers who have gone from harvesting catfish in a conventional multi-batch system to a modular one.

The change, he said, helps him better identify and differentiate large fish from small ones, and thus improve feeding conversions — arguably the most crucial element to catfish farming.

“To me, I want to find as much efficiency in the process as possible so I can increase the feed. If do that, it's worth the change,” he said.

The steps in raising commercial catfish as they mature from fingerlings to food fish and are grouped by size into ponds remain an inexact science because, unavoidably, some fish eat more and grow larger at a faster pace than others. That discrepancy hampers appropriate feeding levels and permits natural competition for food among maturing fish.

But Dees and others rely in their alternative routine on an in-pond mechanical floating grading system developed and modified by David Heikes, an Extension agent with the University of Arkansas at Pine Bluff.

The system aids the modular harvesting practice aimed at reducing the amount of mixed sizes and can be an improvement over the popular method of grading catfish through socks.

Dees called the equipment a “polishing tool” to his modular batching practice. It is composed of an adjustable horizontal bar grader, a trailer with a water pump, and an educator pump system that pushes fish to the grading surface.

“One of our first graders was for food fish, but when we saw (the industry) had a problem grading small fish, we switched gears,” Heikes said.

Within the past five years, about 16 farmers in the region have purchased the grader, created by Heikes, a half-dozen fabricators and students at an Arkansas vocational school. Cost of the grader is between $10,000 and $20,000.

Heikes said the grader design work has “progressed” since its inception about a decade ago. The modified design enables up to three workers to sort 798 pounds of food-sized fish per minute.

Dees said the in-pond grader pump has proven more effective in screening fish during winter months when fish are less active and grouping by size can be harder.

A non-cash advantage is predator control, he observed: “Herons and other species of birds that prey on fish farms are big problems. They like smaller fish over larger fish. If sizes of fish are better separated, farmers can better concentrate deterrence measures.”

Efforts to market the graders have been slow — basically only word of mouth advertising — because of economics in the catfish industry, Heikes said.

“The industry is in a tight price situation, and there is not much money for farmers to invest in new technology. Most farmers are trying to just get by.”

Heikes said it is difficult to persuade farmers to “change their mindset” about long-term advantages from pertinent technology.

The market, however, may force a change. Over the past few years, fish processing businesses have sought larger catfish, increasing average size demand from 1 pound to 1.25 pounds.

The main reason: restaurants prefer to fill up a patron's plate with one fish rather than with two.

The shift in size, Dees said, is substantial. “A change in the market size for fish such as this may not seem like a big deal, but making that fundamental shift in a farming scheme is a huge undertaking.” His farm's transformation happened in stages over three years.

One effect from the market change pertains to pond size. While raising 1-pound fish permits about 7,000 fish on 1 acre, the 1.25-pound fish likely will decrease the number to about 4,700 fish per acre.

Space concerns thus heighten the pressure for farming proficiency.

The single-batch system provides a much more accurate picture of pond inventory. For Dees, that reduces fixed costs about 4 percent overall (based on a market price of 75 cents per pound) provides a relatively quick financial return on the cost of the grader equipment.

Not only are there investment costs for the grader, adjusting from multi-batch practice to modular batching is costly, too.

“In my opinion, this system is probably viable only for a large operation because you have to justify an additional seining labor crew,” Dees said.

Heikes agreed. “Unfortunately it requires more money because you seine more often.”

While he can design a grader for an individual farmer, he would like to see commercial seining businesses offer grading as a service to farmers.

“The adoption of this will be slow until research shows it pays for itself,” he said. “It is slow going, but with time and more information about its effectiveness, it could gain acceptance.”


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