AUBURN, Ala. - Dogs have been enlisted in a scientific effort to halt off-flavor in catfish. A USDA Agricultural Research Service microbiologist has trained dogs to smell water samples to determine which ponds will likely give catfish a muddy — yet safe to eat — off-flavor.

Richard A. Shelby at the ARS Aquatic Animal Health Research Unit in Auburn has teamed up with Larry Myers, an associate professor at Auburn University, who has trained dozens of dogs for police work.

Catfish off-flavor is a problem that costs the industry as much as $50 million a year. Currently producers use one of two methods to check it.

The simplest way is to remove fish from a pond, cook them, and have experts taste the fish for off-flavors. But this is time-consuming and subjective, because even trained personnel taste food differently. Also, producers can use tests, called gas chromatography/mass spectrometry (GCMS), to determine the pond water's levels of the chemicals that cause off-flavors. But this procedure is costly and can take several days.

Dogs, however, can be trained to do the work more cheaply and accurately. Shelby and Myers have successfully trained five dogs, and several of them can smell off-flavor at 10 parts per trillion, a significantly lower concentration than trained human tasters can detect.

Consumers generally can taste an off-flavor at 700 to 800 parts per trillion.

What's more, the dogs don't have to enter the pond to smell the water.

They sniff a small water sample away from the pond. Dogs can be trained to work successfully for a few hours at a time, and can work effectively for seven years or more.

David Elstein is a writer for the Agricultural Research Service, the U.S. Department of Agriculture's chief scientific research agency.

e-mail: delstein@ars.usda.gov