ELECTRIC FISH SCREEN 99 



submit to said State game commission, for its approval or rejection, working models of its [their] 

 respective screens or other devices for the protection of fish. Inadequate screening devices may be 

 ordered removed and new screens ordered installed when, upon investigation by the State game 

 commission or any of its representatives, it is determined that any screen, grating, or other device, 

 either by construction, operation, or otherwise, is found to be inadequate by the State game com- 

 mission. In the event the owner in whole or in part, or person leasing, operating, or having in 

 charge such ditch, canal, mill race, or other artificial watercourse, shall fail or refuse to comply 

 with the instructions of the State game commission with respect to the installation, maintenance, 

 or repair of such screen, grating, or other device within such reasonable time as may be specified by 

 the State game commission, he shall be guilty of a misdemeanor, and said State game commission or 

 any of its representatives shall have power to close forthwith the head gates or place such other 

 barrier or obstruction in such ditch, canal, mill race, or other artificial watercourse as said State 

 game commission may deem necessary to prevent the flow of water through such ditch, canal, 

 mill race, or other artificial watercourse until a screen, grating, or other device shall be placed 

 therein to the satisfaction of the State game commission. 



From the above law it is obvious that there is nothiag lacking in the way of legal 

 authority for the protection of fish from dangerous waterways. Unfortunately, 

 however, the eflfectiveness of these laws has been impaired greatly because adequate 

 screens have been expensive to install and very difficult to maintain. 



MECHANICAL SCREENS 



Mechanical screens of the stationary type, having a mesh of sufficient fineness to 

 afford adequate protection to fish fingerlings, have been found very difficult and 

 expensive to maintain. The chief difficulties are the constant accimiulation of leaves 

 and debris and mechanical injury to the screen by large floating pieces of debris. 



The objectionable features of the stationary-type mechanical screen have been 

 reduced greatly by the revolving, self-cleaning type of screen, which has been available 

 since 1918. However, the revolving screen has not solved the fish-protection problem 

 and leaves much to be desired in the screening of dangerous waterways. 



ELECTRIC SCREEN 



The idea of using an electrified area in water to direct the movements of fish is 

 not new. At least three and perhaps more United States patents have been granted 

 on methods of using electricity for this purpose. The most recent of these patents 

 was applied for in March, 1922, and was granted in November, 1924 (Burkey, 1924). 

 Hence, no claim is made that the idea of an electric fish screen is new or novel. 



Many installations have been made of electric fish "stops" in Washington, 

 Oregon, and Cahfornia. Some of these installations have been considered successful; 

 others have been pronounced absolute failures. As a result of these confficting 

 opinions, the electric fish "stop" came into disrepute in some locaUties and in some 

 instances was abandoned entirely as impractical. Investigation disclosed the fact 

 that, virtually without exception, the installation of electric "stops" had been made 

 by those who had Httle or no knowledge of electricity, and there was an absolute 

 dearth of information about the voltage gradients fish were susceptible to in water 

 and the voltage gradients required to produce paralysis and death. The only fact 

 that was known definitely was that virtually every installation succeeded in killing 

 some fish. Hence, the electric fish "stop" rapidly gained a reputation as a destroyer 



