Effects of High-Frequency Pulsed-DC Electrofishing on a Wild Brown Trout Population

Abstract

Abstract I determined the effects of annual exposure to high-frequency (>800 Hz), pulsed-DC electrofishing on the occurrence of spinal injuries, growth, size structure, and population density of wild brown trout Salmo trutta in a high-alkalinity stream in central Pennsylvania. I compared population statistics of brown trout in a section (section A) of Spruce Creek that was electrofished annually from 1985 to 1996 with those in another section (section B) that was electrofished annually from 1985 to 1991 and again in 1996. The frequency of spinal injuries of brown trout in section A (43.6%) was not significantly higher than that in section B (38.0%). The frequency of spinal injuries in angled brown trout from another section of Spruce Creek that had never been exposed to electrofishing was 15.5%. Median lengths of brown trout (ages 1–3) in section A were greater than those of brown trout in section B. Relative weights of brown trout in section B were higher than those in section A only in 1996, but these d...