February 21, 2013
New methods being used by fisheries biologists
John McCoy
The electrofishing boat, which biologists once used to find out which fish species were present in a body of water, is becoming outmoded now that identification is possible through fish DNA present in the water itself.
Instead of trying to capture tagged fish again and again to track their movements, biologists can now use passive sonar detectors that register each time a tagged fish passes by.
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CHARLESTON, W.Va. -- To biologists, the answers to life's mysteries seem cut and dried -- at least until someone proves they aren't.

Decades ago, fisheries biologists didn't think twice about taking fish from one part of the country and stocking them into another. To determine which fish species were present in a body of water, biologists simply cordoned off an area with nets, poisoned everything within it, and took the fish back to the lab for study.

Times have changed. Biologists seldom approach their work in such blunt-edged fashion anymore, mainly because they've discovered better and more effective ways to accomplish what they set out to do.

Chris O'Bara, a fish biologist for more than 30 years, has seen what he calls "a dramatic change" in the way he and his colleagues conduct their affairs.

"Back when I got started, fish biologists were more like naturalists than scientists," O'Bara said. "To survey a population, we collected specimens by shocking or netting or seining or poisoning them. We looked at what we had, tried to make some sense of it, and tried to figure out what to do about it."

For example, when walleyes began disappearing from West Virginia rivers and lakes during the late 1950s through the 1960s, Division of Natural Resources biologists did what colleagues in other states were doing -- they brought in walleyes from the Great Lakes and stocked them.

"We now realize that was a mistake," said O'Bara, who heads up the DNR's fisheries research arm.

"The reason we know that is because advances in genetics research showed us that the Great Lakes fish have a different genetic makeup from walleyes that were native to our rivers."

Armed with that knowledge, DNR officials are now able to identify native-strain walleyes, breed them in the state's two warm-water hatcheries, and stock them instead of Great Lakes fish.

O'Bara said many of the methods and gadgets fisheries biologists use today were originally used in other areas of biological and biomedical research.

"What we have done is borrow, steal and use approaches that were pioneered in other disciplines," he said.

Gene research, he added, has had a particularly strong influence.

"With the techniques developed in the field of molecular genetics, we are able to tell why some strains of fish do better than others. It started in the early 1980s when people started studying Florida-strain largemouth bass, and it just exploded from there. Nowadays a lot of people are looking at a lot of species, and are applying their findings to fisheries management."

Advances in medical pathology have helped biologists better understand how disease can affect both wild and hatchery-grown fish populations.

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