Fish Health and Genetics Laboratory

Molecular Genetics

When fisheries managers release captive-bred fish into public waters, they often need to collect information on those fish at a later date. For example, it is often beneficial to know how well the hatchery fish survive in the natural environment, if the fish have mixed well with the native population, and if the stocked fish have outperformed the resident population.

For decades, biologists have marked individual fish with physical tags in order to track their progress. Tagging is still useful for short-term studies of small numbers of fish. However, recent advances in molecular genetics have spawned new and more efficient techniques.

Gloved hand places dyed samples in prepared gel.
A researcher loads DNA samples marked with dye into a submarine gel

Scientists can now analyze molecular markers from scale, fin, and blood samples. These markers include both DNA and proteins. For example, certain diagnostic proteins can help distinguish one species from another. For subspecies identification (for example, the Florida strain of largemouth bass versus the native, northern strain), scientists can examine microsatellite DNA (simple, repetitive sequences which evolve rapidly).

The Human Genome Project and similar efforts with other species have contributed a wealth of knowledge and techniques to molecular genetics. This rapidly expanding base of knowledge is available to staff at the Fish Health and Genetics Laboratory through the National Center for Biotechnology Information. A recently acquired Licor 4200 dual laser DNA sequencer has allowed the laboratory to expand its range of analysis techniques to encompass microsatellites, DNA sequences and other DNA based molecular markers. As the study of genomics continues to evolve, TPWD will use these advancements to learn more about how genetics influences fish culture and productivity.

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