Influence of Pulsed Direct Current Electrofishing on Mortality and Injuries among Four Centrarchid Species

Abstract

The effects of pulsed direct current electrofishing on mortality of and injury to largemouth bass Micropterus salmoides, smallmouth bass M. dolomieu, bluegill Lepomis macrochirus, and pumpkinseed L. gibbosus were examined. The pulse frequencies were 30, 60, and 120 Hz, and conductivity categories of 122–214, 456–683, and 752–789 μS/cm were used. Three independent collections were made with nine different combinations of pulse frequency and range of conductivity. Fish were placed in holding pens for 72 h; dead fish were removed and autopsied immediately. Internal hemorrhages were documented by dissection; potential skeletal damage was determined by radiography. After 72 h, one‐fourth of the caged fish were sacrificed and examined for internal hemorrhages. Of 454 largemouth bass collected, 6 died (1.3%) and another suffered external injury. Of 145 smallmouth bass, 1 died (0.7%) and another 5 (3.4%) exhibited external injuries. Of 568 bluegills, 30 died (5.3%). Fifty‐five pumpkinseeds were examined and none died or were injured. Pulsed direct current electrofishing did not cause high mortality; none of the X‐rayed fish exhibited skeletal damage. Mortality appeared to be caused by hemorrhages of the dorsal aorta and other nearby blood vessels in the caudal area.

An evaluation of some electrical waveforms and voltages used for electric fishing; with special reference to their use in backpack electric fishing gear

“…Haemorrhaging of blood vessels along the spinal column as a result of electrical injury is consistent with other research (Bardygula-Nonn et al, 1995) but was low, and both individuals with such injuries had been subjected to the high voltage waveforms. McMichael (1993), in a similar study, found that injury rate was correlated positively with pulse frequency but as pulse widths or rms voltages were not given the results are difficult to compare.…”

Electrofishing Practices Have Limited Effects on Largemouth Bass Feeding Behavior

“…In our study, only one fish (3.4% of total individuals) died soon after being subjected to electric shock. Similar low mortality rates have been MANAGEMENT BRIEF previously observed for electrofished warmwater fishes (e.g., Bardygula-Nonn et al 1995;Dolan et al 2002;Dolan and Miranda 2004), suggesting that our experimental electrofishing protocol was representative of standard electrofishing practices.…”

“…The largemouth bass Micropterus salmoides is a popular sport fish among North American anglers, and the utilization of electrofishing by fisheries professionals during the intensive management of the species could have biological implications. In addition to mortality or injury (Spencer 1967a(Spencer , 1967bBardygula-Nonn et al 1995), sublethal stressors associated with electrofishing practices could affect largemouth bass. An increase in time taken by largemouth bass to resume feeding after being exposed to stressors from simulated recreational angling events (Siepker et al 2006a(Siepker et al , 2007 suggests that similar or greater effects could occur as a result of electrofishing practices.…”

Fish Species in Chicago Harbors of Lake Michigan, 1988 to 1990, as Determined by Electrofishing and Creel Surveys

“…Smallmouth bass were later found in Diversey and Belmont Harbors. As part of another study, we found that by late summer, 1990, young smallmouth bass were more common than young largemouth bass in Diversey Harbor (Bardygula-Nonn et al 1995). The first report of a black crappie in Illinois waters of Lake Michigan was one captured in Belmont Harbor (Savitz et al 1990).…”

“…The white perch was first reported in Illinois waters of Lake Michigan at Belmont Harbor (Savitz et al 1989a). We captured white perch at Jackson Park Harbor and in August, 1990, and we captured white perch at Diversey Harbor in 1991 ( Bardygula-Nonn et al 1995). The first report of quillback carpsuckers in Illinois waters of Lake Michigan was the result of electrofishing at Jackson Park Harbor (Savitz et al 1989b); the quillback carpsucker has not been captured since that time.…”