PART V 



NOTES ON THE RESPONSE OF A TROPICAL FISH ( KUHLIA 

 SANDVICBNS IS) TO INl^ERRUPTED DIRECT CURRENTy/'" 



by 



Albert Lo Tester 

 Professor of Zoology 

 University of Hawaii 



INTRODUCTION 



A study of the reaction of tuna to electrical stimuli 

 was not attempted for the following reasons ^ (1) because of 

 the expense of purchasing a generator of sufficient power to 

 produce a reasonably high current density Csay^ 0,002 amps 

 per square centimeter) in the large (10,663 gallon) concrete 

 tank in which the tuna vrere kept^ (2) because of the danger 

 of harming the tuna, which were being used for other experi- 

 mental purposes^ and mainly (3) because there were indications 

 from the work of Morgan (19^1) that further research could be 

 undertaken profitably with the aholehole or "mountain bass" 

 ( Kuhlia sandvicensis )^ using a tank and generator which were 

 already available., Consequently, with the small amount of 

 time that was available, the author attempted to duplicate 

 and extend Morgan's experiments in an effort to discover the 

 optimum pulse duration for minimum power output to attract 

 aholehole in an interrupted^ direct current system., It should 

 be pointed out that before seriously considering the practica- 

 bility of catching tuna or any other fish by electro-fishing 

 methods nn the high seas,, still more efficient use of the 

 available power than that achieved either by Morgan (195l) or 

 by the Cooperative California Sardine Research Program (anonc, 

 1950) must be made. Otherwise j, the power plant required by a 

 fishing vessel weald be eoctremely large, expensive, and there- 

 fore probably impracticable » 



As the present study represents an extension of Morgan's 

 (1951) work, and as his data are not readily available, his 

 results may be summarized here to advantage o He atten^jted to 

 discover the minimum current which would lead or force 

 aholehole to the positive pole in a column of salt-water 

 (wooderTTank) measuring 12 x 2 x 1 feet, using a source E,MoF<. 

 of 220-230 volts, Do C<, In some experiments thie current was 



1/ Contribution Noo 26 of the Hawaii Marine Laboratory j 

 University of Hawaii^ Honolulu, To Ho 



69 



