Beyond
the Sea:
Research Benefits Aquaculture Production
U.S. aquaculture production expanded
steadily in the 1980s and 1990s and today encompasses a variety of aquatic
animals-species ranging from catfish, trout and salmon to shrimp, clams and
oysters. However, the United States ranks only tenth in the world in the value
of its aquaculture production. Currently, more than 70 percent of the seafood
consumed here is imported. This has resulted in a trade deficit of about $7
billion.
The Agricultural Research Service (ARS) is
doing its part to improve aquaculture practices in the United States to benefit
both producers and consumers through a variety of approaches.
One way ARS scientists help the industry
gain an edge is by using traditional breeding, broodstock development,
germplasm preservation, molecular genetics and related techniques to improve
available aquaculture stocks.
Genetic improvement of species such as
channel catfish, for example, is important for long-term viability of the U.S.
catfish industry. NWAC103, a catfish
line released jointly in 2001-2002 by ARS and the Mississippi Agricultural and
Forestry Experiment Station at the Thad Cochran National Warmwater Aquaculture
Center in Stoneville, Miss., consumed 10 percent more feed and grew 10 percent
faster than channel catfish in production at the time. This line has captured
about 15 percent of market share at this time.
That's a significant economic gain for the
catfish industry, which accounts for over two-thirds of U.S. aquaculture
production and over half the value.
Trout is another valuable aquaculture
commodity. The total value of all sales, both fish and eggs, received by trout
growers in the United States totaled $68.7 million in 2004, an increase of 7
percent from 2003, according to USDA's National Agricultural Statistics
Service. And ARS researchers in Leetown, W.Va., are gaining insight into trout
genetics so they can breed
faster-growing,
disease-resistant fish. At the National Center for Cool and Cold Water
Aquaculture, which opened in 2001, molecular biologist Caird E. Rexroad III and
colleagues are working on a genetic map of the rainbow trout to assist in the
development of improved strains.
Kenneth E. Overturf, an ARS geneticist
with the Small Grains and Potato Germplasm Research Unit at Aberdeen, Idaho,
but based at the University of Idaho's Hagerman Fish Culture Station in
Hagerman, has selected certain rainbow trout among different strains that
perform well on grain-rich feed. Feeds
are the fish farmer's biggest expense and are usually made with fishmeal from
saltwater species. Using more grain in fish feed would help prevent overfishing
of these saltwater species. ARS research geneticist Victor Raboy, based in
Aberdeen, Idaho, developed barley and other grains that contain less phytate, a
form of phosphorous that is difficult for fish to digest. These trout gain
weight when fed specially bred grain and excrete less phosphorous in their
manure and into bodies of water. Phosphorous pollution has been blamed for
algal blooms that deprive fish of oxygen.
Using improved technologies and practices
such as vaccines and therapeutic treatments as well as disease detection and
diagnostic techniques, ARS researchers are working to help producers improve
the survival, growth, health and wellbeing of their fish and shellfish.
Diseases that impede fish growth or kill them result in less profit for the
producer and higher prices for consumers.
Over the past few years, the ARS Aquatic
Animal Health Research Unit in Auburn, Ala., has either patented or applied for
patents for several new fish vaccines. Researchers at the Auburn unit and their
laboratory in Chestertown, Md., are working with catfish and-to a lesser
extent-with tilapia, hybrid striped bass and several other fish species.
ARS microbiologist Phillip H. Klesius and
ARS molecular biologist Craig A. Shoemaker previously developed a vaccine
against the bacterial disease enteric septicemia of catfish (ESC). Their
vaccine was the first modified live fish vaccine to be approved, and it
significantly reduced catfish mortality. Now,
two new ARS-developed
vaccines for catfish and other fish species offer protection against the
pathogen Flavobacterium columnare. Another vaccine treats
Edwardsiella tarda.
In order to boost U.S. aquaculture
production, ARS researchers are finding ways to improve the growth and
development of different species by studying how they convert feed and tolerate
different environments.
For example, hybrid striped bass
production began in the mid-1980s and is now a major aquaculture industry.
Findings from the Harry K. Dupree Stuttgart National Aquaculture Research
Center in Stuttgart, Ark., could be instrumental in the development of a
year-round supply of hybrid striped bass (also known as sunshine bass)
fingerlings. Developing new methods for rearing fry indoors
increases production of
fingerlings. Indoor production is required for producers working in
temperate climates. Biologist Gerald Ludwig produced hybrid striped bass fry in
indoor tanks for the first time by feeding them freshwater rotifers, which he
also cultured indoors. Typically, sunshine bass fry are raised in outdoor
rearing ponds until they're 35-40 days old, when they become
fingerlings.
Les Torrans, at the Catfish Genetics
Research Unit in Stoneville, co-developed an improved method called the
"Sock Saver" for
supplying farm-raised catfish with oxygen during a crucial production stage. He
and colleagues designed and built equipment for using liquid oxygen (LOX)
during harvest, which increases dissolved oxygen and reduces stress losses of
fish.
The research projects mentioned here are
just a few of the ways ARS researchers are demonstrating that there is
potential for future growth in U.S. aquaculture. The ARS national program for
aquaculture is committed to helping offset dependence on imported seafood and
helping assure safe, affordable, high-quality and appealing products for U.S.
consumers. For more information, visit the
program
website. |
Research Briefs
The donation of a large bull semen collection to
ARS will help breeders preserve genetic
diversity in beef and dairy cattle.
A discovery by ARS researchers involving cow
fertility could help boost artificial
insemination production.
ARS scientists have found that
Cryptosporidium parvum infections in calves are
not as common as
previously thought.
Two new ARS-developed
vaccines for catfish and other fish species offer protection against the
pathogen Flavobacterium columnare. Another vaccine treats
Edwardsiella tarda.
The biting midge has been implicated in the
transmission of vesicular stomatitis
virus to livestock and wildlife, according to ARS researchers.
ARS researchers are working with the Navajo
tribe to preserve the
genetic material of Navajo-Churro sheep.
Transgenic cows produced by ARS scientists
contain antimicrobial
proteins in their genes to resist mastitis.
Healthy
Animals archive |
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