One of the South’s favorite foods is Mississippi pond-raised catfish.
In fact a recent Mississippi State Extension Service article maintained that Mississippi sits right, “In the middle of the six-state radius that consumes the most catfish,” but most consumers do not realize how much research, scientific technology and study goes into making sure the appetizing aquatic remains a viable crop for farmers.
Mississippi Valley State University physiology professor, Rachel Beecham, PhD., has worked for Mississippi State at Stoneville and spent countless hours studying catfish physiology, mating habits, disease control and more.
The MSU Delta Research and Extension Center in Stoneville has been a nucleus for much of the advancements and improvements in catfish farming in Mississippi. In her research, Beecham has discovered much to aid in the success of fish farming as an industry,
“Everything I’ve done was to help the farmers,” she said.
But competition from foreign importers, among other things, has led to economic loss in the catfish industry in the U.S. and in Mississippi, prompting some producers to repurpose acreage that had been used as catfish ponds for other crops. Small farms are closing and, whereas a farmer may have been raising multiple crops including fish, it may not be profitable to operate just a few small ponds.
Beecham said nowadays a great many smaller farmers have stopped trying to produce fish as a crop and yielded the process to farmers who have larger operations. Some ponds are six to ten acres large.
According to Alex Deason, MSU Extension Service, “As a county, Sunflower has dropped from 7,644 acres in 2013 to 3,916 acres last year. Production has had some strains (but) the lower feed costs has been a huge help in keeping catfish production costs down.”
Beecham worked in Stoneville at the AG center before coming to MVSU and has done a lot of catfish work. A large portion of her research has been in the direction of determining the fish’s stamina. “I study more what goes on to make them do different things.” She has also studied the diseases that affect the fish such as Proliferative Gill Disease also known as hamburger gill disease.
The fish take in water that passes through the gills and the process extracts the oxygen from the water but in PGD, the gills become like hamburger and cannot function properly. Another condition is known as fisheral toxicosis, a condition that causes the fish to become paralyzed and if they cannot swim, then they cannot take in oxygen. “Obviously we lose a lot of fish,” she said.
She studies oxygen levels in the fish to try and determine ways that will help them exert less energy thereby living longer, growing larger and providing better income for the farmer. The bigger the fish the more you get paid at market, she said.
But there are some problem areas in raising and harvesting fish. Beecham described how the oxygen levels in the ponds get low during the summer at night, so paddle wheels are used to aerate the ponds. The paddle wheels are needed because phytoplankton and algae form on the ponds and during the day they produce oxygen, but at night they photorespire and deplete the oxygen in the water.
“The fish have to swim behind those to get oxygen,” she said, and the paddle wheel can generate currents up to 100cm per second near the wheel and that causes the fish to use a great deal of energy. So she and other researchers conduct studies aimed at making farming sustainable by trying to keep the oxygen levels up so the farmers don’t lose fish and cost them money.
She explains that a living thing has only so much energy to grow and so much energy to do the things it does, “It is a balanced equation.” So if the fish use a lot of energy to swim behind the paddlewheel it affects their rate of growth.
Therefore the speed of the paddlewheel and the efficiency of the fish to swim at different sizes of growth were studied so they could adjust the aerators to put out enough oxygen but also hit the “sweet spot” for the fish, so they get the oxygen they need without having to over exert themselves. Beecham explained that it takes energy to start swimming, but at some point it takes less energy to keep swimming, so they are trying to match that to maximize oxygen and not inhibit the catfish’s growth.
The male fish does all of the work in catfish spawning. In controlled environments they spawn in large milk cans, in the wild it may be under an old tree limb or ledge, someplace hidden. About 10 to 15 cans are usually put in a small pond with a big broodfish.
The broodfish cleans the can, calls to the female by making a noise on his fins, then the two do a swimming-around courtship ritual all the while making sounds. The female then lays eggs in the can, a few at first, then more, up to hundreds of thousands. The male swims over the eggs and fertilizes them and the female swims away because she is done. He stays, fans the eggs to give oxygen and protects and hatches them.
Producers then remove the cans from the water, careful to make sure the male fish has exited because he will bite to protect the eggs if anyone reaches in while he is there. The eggs are brought to the hatchery and grown. In lean years when the fish do not spawn, they can inject the female fish with a releasing hormone that makes her ready to push the eggs out if she cannot release them on her own.
They do this to protect the female because the male fish will run her off or kill her if she does not produce. “It’s still natural, they are taking the sperm from the male, pushing the eggs out of the female, it’s the same process, its just that we are using our fingers to push the eggs down her belly,” said Beecham. She added, that’s also how hybrids are made, but the hybrids do not breed.
The ponds are seeded with small fish about 6-8 inches in length. At harvest the farmer generally does not know how many fish are still in the pond, he knows how many he put in, but snakes, birds, and such come and eat some of the fish. The average pond is only four to five feet deep.
Harvesting the fish involves using a big net called a seine that has weighted bars that they drag across the bottom of the pond and the fish that are large enough to be harvested are caught up and the smaller ones swim out through the holes in the net.
Beecham said there have been lots of improvements for the farmers by measuring the speed at which the fish swim and how much energy it costs them to swim at certain speeds. She said, “The idea is to grow them out to market size as fast as you can.”
And what consumers usually end up with on their plates is either channel catfish or a male blue catfish/female channel catfish hybrid according to Beecham. They breed the blue and the channel catfish together, because the hybrid has characteristics that they like, it produces a better fillet quality and is a faster growing fish.
Beecham asserts that they are not manipulating the genes at all, they are simply choosing the best characteristics. “Just natural, everything I did was natural. It’s all selective breeding.”
She also dispels the myth that catfish are “bottom feeders.” The fish raised in ponds are very clean, Beecham said they feed on pellets and foods produced at a local facility and even those feeds are researched to determine how much protein and such needs to go into the foods the fish eat.
Beecham earned her PhD at Ole Miss. It was there that the Pittsburg native met a researcher from Stoneville, which initiated her interest. She conducted research there and hooked a job at Mississippi State. The Steelers fan said she landed in the Delta and just stayed. “The Delta is awesome,” she added.
Beecham teaches a consistently full aquatic biology class at Valley where they study, types of fish, conduct water samples and many physiological experiments with things other than fish.
She teaches human anatomy and physiology plus the seniors must complete and present a research project. Students interested in pre-med, dentistry, physical therapy, optometry or nursing are enrolled in the department, “Our curriculum allows them to go into any of those fields,” said Beecham.
