CONTENTS 



Page 



Introduction 1 



The Type IV shocker 1 



Description of the shocker 2 



Characteristics and effectiveness of the energy output 3 



Effects of basic electric currents 3 



Optimum pulsed d.c. for electrofishing 5 



Effect of voltage on fishes . 5 



Effect of repetition rate and duration of a pulse 5 



Wave shape 7 



Output voltage 8 



Amperage 8 



Output energy of the shocker 8 



Methods of operation of electric shockers 9 



Electrodes 9 



Electrofishing techniques 9 



Considerations for electrofishing 12 



Influence of water resistivity 12 



Intraspecific and interspecific variation in fishes. . 12 



Effects of temperature 12 



Injury to fish 13 



Summary 13 



Literature cited 14 



