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Genetic Stock Improvement

The use of genetic improvement is not new to agriculture, although it is relatively new in the aquaculture industry. Although carp as been genetically manipulated for thousands of years the application of modern genetic improvement techniques is still being developed in the aquaculture industry. Genetic engineering can take two forms, the first is domestication which results over time in a managed species. This process has been going on for thousands of years with animals such as cattle and poultry, thus their high level of domestication. The second technique of genetic engineering is actively manipulating the genetics of various organisms or species. This process can include selective breeding, chromosome manipulation, hybridization, development of single sex groups, and gene tranfer.Most directed genetic manipulation is desinged to enhance or introduce favorable growing or endurance traits into an organism that is going to be cultured. The hybrid striped bass is a product of hybridization in which the striped bass was crossed with the white bass. Other species that have been improved through transgenic techniques include carp, atlantic salmon, tilapia, and coho salmon. Although hybridization has succeeded with the hybrid striped bass, the most promising genetic method in developing a long term feasible genetically improved species is selective breeding, in which the reproduction of the species is carefully monitored and controlled to prevent the transmission of unfavorable traits and encourage the transmission of favorable ones to the next generation.

Another technique used to increase production is to hormonally control the sex of the cultured animals. In many species one sex grows larger than the other so it is favorable to produce more of the larger sex.

In general most genetic improvement programs have resulted in increased production. Several examples of stocks that have been genetically enhanced for culturing are the Atlantic salmon in Norway, tilapia in the Philippines, oysters in North America, and catfish in the United States. Many of the genetic improvement techniques have become practical for commercial purposes and are now being used to increase production and address biological pollution problems.

There are objections to the use of genetic techniques, as listed by the FAO, these include:

Transgenic species may escape into the wild, disrupting wild populations.
The genetic changes could be passed on to wild fish
Consumer rejection of genetically altered fish
Genetic changes could cause human health problems
Animanl wellfare may be compromised
Ethical considerations regarding genetic manipulation

In response to these issues, developmental guidelines are being developed such as standards produced by the U.S. Department of Agriculture, and internationally by international agreements such as the FAO's Code of Conduct for Responsible Fisheries.