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United States Department of Agriculture

Agricultural Research Service

Healthy Animals Newsletter

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Issue 23, October 2005
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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.

Geneticist Ken Overturf handles a female trout.

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.


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Last Modified: 2/6/2007
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