(2) pulse frequency, and (3) pulse duration 

 for leading adult squawfish within an elec- 

 trical array; and (B) the possible signifi- 

 cance of the direction of movement of the 

 electrical fields. 



Acknowledgments 



The research reported here, conducted 

 in 1956, was made possible with funds for 

 Squawfish control studies from the Lower 

 Columbia River Program, U. S. Fish and Wild- 

 life Service. Acknowledgment is made to 

 personnel of the Fish and Wildlife Service 

 hatcheries of the Lower Columbia River for 

 use of holding facilities. Joseph Gauley 

 and Ben Pulliam collected adult squawfish 

 at Bonneville Dam, and Clifford Davidson 

 cooperated in the collection of squawfish 

 at Rock Island Dam. Archie Anderson, Oregon 

 Fish Commission, gave the use of a holding 

 pond at Bonneville Hatchery; Dr. Lauren R. 

 Donaldson, University of Washington, per- 

 mitted the use of several holding ponds at 

 the School of Fisheries in Seattle. 



Especial appreciation is expressed to 

 Dr. Douglas G. Chapman, Department of Mathe- 

 matics, University of Washington, for 

 reviewing the statistical treatment of the 

 data and to Paul Zimmer, Fish and Wildlife 

 Service, Portland, Oregon, for his efforts 

 in furthering the research. 



METHOD 



We designed these experiments (1) to 

 proceed from the results of our preliminary 

 experiments, (2) to use most advantageously 

 a limited supply of squawfish, (3) to over- 

 come the inability to reverse readily the 

 direction of the electrical fields, and (4) 

 to use standard experimental procedures in 

 measuring the leading effectiveness of 

 electrical conditions. 



Experimental Design 



1. Preliminary observations on indi- 

 vidual fish defined the working ranges of 

 potential, pulse frequency, and pulse dura- 

 tion, as follows: Potential, 60 to 90 

 volts; pulse frequency, 2 to 8 pulses per 

 second; and pulse duration, 10 to 30 milli- 

 seconds. Intermediate values were tested 

 in each range to determine whether the 

 ranges included optimum electrical conditions 

 for leading adult squawfish. Inclusion of 

 these intermediate values increased the 



number of possible combinations of values 

 of potential, pulse frequency, and pulse 

 duration from 8 to 27. These 27 combina- 

 tions in the experimental design were set 

 up as a series of tests. 



2. As more than one test at each 

 combination in the series was needed to 

 determine whether the effects of one vari- 

 able factor depended upon the values of one 

 or both of the other variable factors, the 

 number of tests required in relation to the 

 number of fish available for use in the 

 tests was such as to require using each 

 group of fish twice. Furthermore, it was 

 not possible to test every combination of 

 the three variable factors with both un- 

 shocked and once-shocked fish before pro- 

 ceeding to the next combination. 



3. As we had no facilities to control 

 the temperature of the water in the experi- 

 mental tank, we anticipated a temperature 

 decrease throughout the experiments from 

 late summer to fall. 



4. It was not possible readily to 

 reverse the direction of movement of the 

 electrical fields in the laboratory tank, 

 but it was of some interest to determine, 

 if possible, whether the direction of the 

 electrical fields had a significant effect. 



5. On the basis of readings taken at 

 release areas, the resistance of the water 

 was maintained at 15,000 ohms per cubic 

 centimeter throughout the experiments. 



Based on our preliminary work, the 

 possibility existed that the fish could 

 show a preference for the north or south 

 end of the experimental area. This could 

 be determined readily if the direction of 

 the electrical fields could be reversed 

 quickly — a combination could be tested 

 with the movement of the electrical fields 

 first in one direction and then in the 

 other. However, preliminsiry observations 

 indicated that, with the power off, a pro- 

 hibitive number of fish would be required 

 to demonstrate the presence or absence of 

 a preference of the fish for one end of 

 the laboratory tank. 



The use of the north and south blocks 

 of tests arose from the time-consuming 

 procedure that would have been necessary 

 in order to alternate the direction of move- 

 ment of the electrical fields. All combi- 

 nations were tested in separate series with 



