• Injury, survival and growth of rainbow trout captured by electrofishing

      Taube, Thomas Theodore (1992-05)
      Electrofishing injury studies in Arizona and Alaska revealed spinal injury rates of over 50% among large (>300 mm long) rainbow trout Oncorhynchus mykiss captured by electrofishing with pulsed direct current (PDC). My goal was to identify an alternative waveform that would efficiently capture large rainbow trout with injury rates less than 15%. Experiments in homogeneous and heterogeneous electrical fields tested six waveforms; lower injury rates resulted with DC (17%), CPS™ (8%), and 20-Hz PDC at 75% duty cycle (25%). In field experiments with these three waveforms, PDC and DC gave higher capture rates than CPS™. However, injury rate was 60% with 20-Hz PDC and highly variable (0-47%) with DC. Long-term mortality of rainbow trout shocked with 60-Hz PDC at 50% duty cycle was 35% after 203 days. I recommend DC as an alternative to PDC waveforms for relatively safe and efficient capture of large rainbow trout.