ABSTRACT 



Development of electromechanical devices permitted practical application, of sea- 

 lamprey control in Great Lakes streams. The barriers were energized by 110-volt, 

 60-cycle, alternating cui rent. 



Sea lampreys were effectively blocked in their upstream spawning migration. 

 Traps were installed in the control structures to pass migratory fish upstream. The 

 extent of fish mortality at the electrical barriers was influenced by stream velocities, 

 conductivity of the water and stream bottom, and size and location of the traps. 



Biological data on the sea lampreys were collected at the control structures. 



Each stream appeared to have its own electrical characteristics. Several factors 

 influencing the electrical fields were determined. Present information indicates 

 limited possibility of improving the electrical field to reduce fish mortality. 



CONTENTS 



Page 



Electromechanical control structures 1 



Sea lampreys and fish caught or killed 3 



Sea lamprey 3 



Migratory fish 17 



Factors of fish mortality. 17 



Biological characteristics of the lamprey spawning runs. 18 



Electrical features of streams and related problems 21 



Literature cited 26 



