The many problems involved in making fish collections and population surveys in trout streams of the Shenandoah and Great Smoky Mountains National Parks led to an investigation of electro-fishing methods. These softwater streams have electrical resistivities ranging as high as 117,000 ohms cm3. Grounded electrode systems of conventional design proved ineffective in such waters. The Petty-type, alternate-polarity electrode system of original and modified design has been successfully tested in Park streams having resistivities of 32,000 to 117,000 ohms cm3. The addition of trailers to the electrode system has produced substantial improvements in the strength and range of the effective, electrical field in the water. The alternating current power sources for the electrodes include a gasoline-driven portable generator and a battery-powered backpack unit which produce 240 and 250 volts respectively.
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Lennon et al. (1957) studied this question.