Shocking Results: Assessing the Injury Rates of Fishes from Pulsed-DC Electrofishing

Research conducted on electrofishing injury to salmonids resulted in a general consensus that PDC electrofishing is less injurious than AC electrofishing.  Recent studies focused on non-salmonids suggest that PDC electrofishing can cause significant injuries.  We collected bluegill, channel catfish, largemouth bass, gizzard shad, silver carp, freshwater drum, and common carp from the Mississippi and Illinois rivers to test susceptibility of fishes to injury from PDC-Boat electrofishing.  Of these species, only silver carp and channel catfish had injuries.  Channel catfish had a 26% injury rate, and silver carp had an injury rate of 62%.  Injury rate was significantly different for silver carp between the Mississippi and Illinois rivers.  Subsequent analyses revealed that power output, conductivity, and length group played a significant role explaining injury rate for silver carp.  Channel catfish injury rate did not vary with any of the factors tested.  Duty cycle appears to influence injury rates of silver carp, as reducing pulse frequency to 30Hz reduced injury rate to 33.3% and increasing pulse frequency to 120Hz increased injury rate to 70%.  Further study is needed to determine if other species are injured by PDC electrofishing and whether PDC electric fields can be used to manage silver carp.