Results 



7 to 70 kilocycles per se cond 



Experiments at supersonic frequencies were performed in 

 the tankj in which one yellowfin was presento Under control 

 conditions J the yellowfin spent about the same period of 

 time in Area S as in Area Qo 



Supersonic sounds of frequencies of 7$ 10,, and in steps 

 of 5 kilocycles thereafter up to 70 kilocycles were generated^ 

 each for a period of one-half hour, and the reactions of the 

 yellowfin were observed and recorded o As the results vfere 

 negative 5, the data are not included in this reporto In each 

 case 3 the time spent in Area S was about the same as that 

 spent in Area Qo 



In these experiments there was no way of knowing whether 

 or not the transducer of the OCP-1 equipment was generating 

 a signal, because at the time, a separate hydrophone was not 

 available. It seems reasonable to assume that it was func- 

 tioning^ as it had been used successfully as a hydrophone in 

 a previous experiment » The resiilts indicate^ therefore ^ that 

 the tuna was not affected by a steady sound of frequency 

 between 7 and 70 kilocycles per second 3 



$00 to 5y000 cycles per second 



These experiments were also performed in the tank^ using 

 the P-H sound generator and the NEL receiver,. Tests:, each of 

 20 minutes duration^ were performed using 500^, 1^000, 2,000, 

 3j,000, li.OOO, and 5,i000 cycleso The series was repeated three 

 times In none of the experiments was there any definite 

 reaction o 



To deterraiae whether the yellowfin reacted to a sound fre- 

 quency other than, that used above, the audio oscillator was 

 varied continuously between 100 cycles and 10 kilocycles. 

 There was no noticeable reaction o 



100 and 200 cycles per second 



As there was the possibility that the tuna in the tank may 

 have become acciistoraed to strange noises^ such as those emanat- 

 ing from the pumps, the apparatus was moved to the large pond 

 where a yellowfin and tunny were presento After a few hoiirs of 

 work, the test came to an abrupt end when saltwater leaked into 

 the transducer, short-circuiting it, and burning cut the power 

 output transformer in the amplifier,, The fish in the pond 

 died before a new transformer could be procured^ thus terminat- 

 ing the experimental work. 



6U 



