EFFECT OF ELECTRICAL PARAMETERS ON YOUNG SALMON 



229 



Elecrrode Row 



Figure U.— Electrical field created on the third pulse of 

 the cycle when the array was wired according to wiring 

 pattern I. (Lines connect points of equal potential; 

 numbers show percentage of the applied voltage. Heavy 

 dots represent the electrodes.) 



Electrode Row 



A 



B • • • • • 



C • • • • • • First Pulse 



A • 



B • • • • # 



C 5fe^^;^;^A5fe^:^°)0 Second Pulse 

 D ^^^^^^^^^^« 

 E '°- 



C ^^^^^^^^^^0 Third Pulse 



D 



E 



C • • • • • • Fourth Pulse 







E 



30 



B  1 1  • ao 



so 



C "5 i m i i ^60 Fifth Pulse 



D * S S C • 80 



Figure 12. — Electrical fields created during one com- 

 plete cycle when the array was wired according to wiring 

 pattern II. (Lines connect points of equal potential: 

 numbers show percentage of the applied voltage. Heavy 

 dots represent the electrodes.) 



the applied voltage. Figure 1 1 shows the electrical 

 field produced when the array was wired according 

 to wiring pattern I. Only one pulse of the five- 

 pulse cj'cle is illustrated, but it is representative 

 of the electrical fields produced with each pulse, 



since the wiring pattern was uniform with respect 

 to electrode spacing. 



Wiring pattern IT was not uniform with respect 

 to electrode spacing, and therefore each pulse 

 created a slightly different electrical field. The 

 electrical fields established when the arraj' was 

 wired in this pattern are shown in figure 12. 



Experimental procedure 



Before the start of each test the electrodes were 

 connected to create the desired wiring pattern. 

 The sequential switching equipment was turned 

 on and, with a calibrated oscilloscope as a monitor, 

 was adjusted to supply the correct pulse param- 

 eters. When the switching equipment was func- 

 tioning properly, it was turned off until the test 

 fish had been placed in the release box. 



Water resistivity was measured by means of a 

 commercial conductivity bridge and regulated to 

 the desired level by adding rock salt or bj' draining 

 the tank and adding fresh water. Facilities were 

 not available to control water temperature, and 

 it varied from 63° F. at the beginning of the 

 experiment (September 16, 1959) to 59.5° F. at 

 the end of the experiment (October 14, 1959). 

 Temperature readings were taken with a standard 

 mercury thermometer. 



Before each test, approxunately 100 fish were 

 transferred from an outdoor holding tank to the 

 rectangular troughs in the fish-behavior laboratorj^ 

 for marking. Then, in groups of 10, the fish were 

 anesthetized in a solution of tricaine methanesul- 

 fonate (M.S. 222) at a concentration of 1:20,000, 

 and tattooed with mineral pigments. When ap- 

 proximately 100 fish had been marked, and all 

 had recovered from the anesthetic, they were 

 placed in the release box in the test channel. In 

 order to observe and remove mortahties due to 

 handling, the fish were held in the release box from 

 10-15 minutes before the tests were initiated. 



The array was then energized with the preset 

 electrical conditions and a pump was started to 

 provide a flow of water through the channel. Next, 

 the sliding gate on the release box was raised, and 

 the fish were released. When all of the finger- 

 lings had left it, the box was hoisted clear of the 

 water by means of the block-and-tackle assembly. 



To ensure that all of the fish were exposed to the 

 electrical energy, they were forced to swim 

 through the array by crowding them with a 

 seine. They were then captured in the recovery 



