The results of the experiments indicated that with few exceptions the difference 

 in the effectiveness of the 40° and 60" angles of electrical field were not significant; 

 this was also true for 1/2 -inch and 2 -inch electrode diameters. There is a question 

 of whether the size of the experimental area was large enough to allow a valid 

 comparison of these factors . The effectiveness of the two angles of field and the two 

 diameters of electrodes should be examined under field conditions. If this lack of 

 significant difference is verified in the field, a considerable saving can be realized 

 in the cost of installation and operation by establishing a 60° angle and using 1/2-inch 

 electrodes. However, it is recognized that the effectiveness of the angle of electrical 

 field may be a function of water velocity', numbers of fish or species of fish. These 

 factors should be examined and the relationship to the effectiveness determined. 



Since some of the fish experienced difficulty in escaping an area in the vicinity 

 of the positive electrodes of a single d.c. field, experiments are in progress to exam- 

 ine the effectiveness of multiple fields of increasing intensity. A pulsating direct 

 current of a higher intensity is necessary to divert fingerlings than is required for 

 larger fish. By creating a zone of lov/ intensity upstream the large fish may be diverted 

 without injury before they reach the zone of higher intensity necessary to divert 

 fingerlings . 



During the experiments it was observed that the fingerlings entered the electrical 

 field and oriented to the positive electrodes before they were diverted. An investigation 

 is in progress to explore the effectiveness of a single line of electrodes with an 

 electrical field of high intensity in an effort to divert the fingerlings before they reach 

 the barrier. Additional tests are planned to investigate the result when the electrodes 

 are energized sequentially. 



SUJvIMARY 



1 . Exploratory experiments v/ere completed under laboratory conditions using . 

 lines of vertically suspended electrodes with the positive line of electrodes parallel 



to and upstream of the negative line of electrodes arid placed at an angle to flowing 

 water . 



2. The electrodes were energized with interrupted direct current of a square 

 wave form with the following electrical characteristics: (1) a pulse frequency of 8 

 pulses per second (2) a pulse duration of 40 milliseconds, and (3) an average voltage 

 gradient of 1 volt per centimeter. 



3. Hatchery-reared silver salmon ranging in size from 5.5 cms. to 12.0 cms. 

 were used in the experiments . 



40 



