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Purrfecting the Catfish
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Market-size USDA 103 catfish ready for harvest.
This new variety grows faster than other tested catfish.
(K9216-9)
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Whether blackened or fried, baked or
broiled, catfish is a favorite catch, particularly in the South. Now, eaters
and producers alike should have no problems finding the "purrfect"
fillet.
Research to develop meatier, tastier, and faster growing catfish is paying off.
Agricultural Research Service scientists
at the Catfish Genetics Research Unit (CGRU) in Stoneville, Mississippi, have
bred a new catfish variety—USDA 103—scheduled to be made available to
catfish producers in February 2001. ARS will release the new catfish jointly
from the Thad Cochran National Warmwater Aquaculture Center with the
Mississippi State University Agricultural and Forestry Experiment Station,
Mississippi State, Mississippi.
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Bill Wolters (center) and Catfish Genetics Research
Unit staff members (left to right) Elijah Allen, DeMarcus McKinley,
and Wesley Sealey, examine USDA103 catfish in an experimental
pond.
(K9216-1)
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It's one of the few times genetic
research has improved catfish since the industry started in the United States
during the late 1950s. Since then, catfish has become one of the most
successful aquacultural enterprises. Genetic research on channel catfishthe
most commonly used species—began in the mid-1960s. But producers have been
waiting for development of a new higher performing catfish variety. Since the
industry's inception, genetic improvement has not had a significant effect on
commercial production in the major catfish-producing states—Alabama,
Arkansas, Louisiana, and Mississippi.
The release of USDA 103 should change that. "It usually takes catfish 18
to 24 months to go from birth to market. This new catfish variety grows 10 to
20 percent faster in the pond, and it's ready for market sooner than other
varieties—an advantage for producers," says geneticist William R.
Wolters, who heads the CGRU.
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The fat level of a live, anesthetized catfish
can be measured with bioimpedance techniques, as demonstrated
by technician Michael Patterson (seated) and animal scientist
Terry Bates.
(K9219-1)
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USDA 103 consumes 10 to 20 percent
more feed than other catfish. But since the feed costs only 10 cents per pound,
producers are gaining a return on their investment because they can often get
70 to 80 cents per pound for the fish.
"This new fish also has good reproductive characteristics," notes
Wolters. "Some USDA 103 catfish can reach sexual maturity at 2 years of
age—a year faster than current catfish. The new variety starts producing
eggs sooner and produces more eggs than some fish now raised
commercially."
"I think this new variety is great," says catfish farmer H. Austin
Jones, who raises about 35 million catfish fingerlings (small fish) and 3
million food fish on 1,045 acres of water in Moorehead, Mississippi. "I
only have one growing season to get my fish ready, so I'm excited about USDA
103 because it will mean I can get a larger fish to the market faster,"
Jones says.
This new fish is the cat's meow. In taste tests comparing it with other catfish
lines, a quality panel selected cooked USDA 103 fillets as one of their
favorites. Wolters says the quality of fresh, frozen, and cooked fillets is
comparable to that of other popular catfish strains. |
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Technician Myrtis Ford holds a fish from a research
study designed to measure the growth rate of USDA 103 line catfish.
(K9222-1)
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New Tools Spawn Better Fish
Aside from genetics, high-tech instruments are helping to boost catfish
production. ARS geneticist Brian G. Bosworth is using ultrasound to see the
internal anatomy of catfish. It's the same technology that allows an expectant
mother to see her baby—and even possibly predict the child's health.
Ultrasound uses reflected sound waves to produce a gray-scale image of the
catfish's internal anatomy. Different tissues have different reflective
properties.
"Using an ultrasound machine, we can measure the size of the muscle,"
Bosworth says. "From that measurement we can estimate the fillet yield of
a live catfish." Fillet yield is the meat from the whole fish. The cattle
and swine industries use this technology to measure carcass traits, like
backfat and loin area, but no one has ever used it to measure fish muscle mass.
"Ultrasound measurements are a good indication of which fish have higher
fillet yield. Now we're breeding those fish to see if they produce offspring
with higher fillet yields," Bosworth says. |
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Cultured channel catfish are typically processed
on machines. Research geneticist Brian Bosworth examines catfish
fillets after processing.
(K9217-1)
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Bosworth is adapting another
procedure from human medicine to predict the fat content in catfish. Typically
used to quantify lean muscle mass, total body moisture, and body fat,
bioimpedance measures resistance to a harmless, low-level electrical current
passed through electrodes in live, tranquilized fish. Resistance is related to
the amount of water and fat in the fish. The more fat, the more resistance.
Using this method, Bosworth says he can measure fat levels in live fish and
determine which fish would make the best genetic contribution to developing a
low-fat catfish.
Another phase of the research involves evaluating fillet yield in different
catfish families. "Members of a family have some genes in common, so by
determining how similar the yield is in family members, we can get an idea of
which fish have the best genes for increased fillet yield," Bosworth says.
"Measuring and evaluating traits in families has been used in other
livestock species, but we are just starting with this approach in
catfish."—By Tara
Weaver-Missick, Agricultural Research Service Information Staff.
This research is part of Aquaculture, an ARS National Program (#106)
described on the World Wide Web at
http://www.nps.ars.usda.gov/programs/appvs.htm.
William R. Wolters and
Brian G. Bosworth are in the
USDA-ARS Catfish Genetics
Research Unit, P.O. Box 38, Stoneville, MS 38776-0038; phone (662)
686-3596, fax (662) 686-3567. |
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"Purrfecting the Catfish" was published in
the January
2001 issue of Agricultural Research magazine.
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