EFFECT OF ELECTROFISHING CONFIGURATION ON CRAPPIE IMMOBILIZATION  SUCCESS AND 
INJURY.  

Chad R. Dolan1, L.E. Miranda2, and T.B. Henry3.  
1Iowa Department of Natural Resources, Lake Darling Station, Brighton, IA 
52540, 2Mississippi Cooperative Fish and Wildlife Research Unit, Mississippi 
State, MS 39762, 3Department of Fisheries and Allied Aquacultures, Auburn 
University, AL 36849.

Continuous direct current (DC) and pulsed direct current (PDC) of varying 
frequency and pulse width, are commonly used to immobilize and collect 
crappie Pomoxis spp. in freshwater. However, little information is available 
about minimum thresholds required for immobilization relative to 
electrofishing configuration, and how these relate to incidence of injury. We 
investigated the effect of escalating power densities on immobilization and 
injury of black crappie P. nigromaculatus for DC and various PDC 
configurations. Forced swimming toward the electrodes was observed in crappie 
exposed to DC, but less so for fish treated with PDC. Minimum power densities 
required to immobilize crappie ranged from 0.09 to 6.5 mW/cm3, and depended 
on pulse frequency and width. Injury, including hemorrhages, vertebral 
damage, and mortality, averaged 5 and 28 % at power densities below and above 
the immobilization thresholds, respectively. However, level of injury also 
depended on pulse frequency and width.

Keywords: crappie, electrofishing configuration, minimum thresholds, 
immobilization, injury

Chad R. Dolan
Iowa Department of Natural Resources
Lake Darling Station
110 Lake Darling Road
Brighton, IA  52540
Phone: 319-694-2430/Fax: 319-694-2309
chad.dolan@dnr.iowa.gov

Platform presentation

No, I would not be willing to convert to the poster format.