Such results as were obtained are discussed briefly^ as 

 they indicate a possible reaction to sound by the yellowfino 

 The reactions of the tunny were also observed^ but were 

 rarely recorded because of the difficulty of timing two fish 

 at onceo The tunny's behavior vfas independent of that of the 

 yellowfin^ and it tended to remain in Area (^, 



Under control conditions j with the apparatus in position 

 but not in operation, the yellowfin spent about 6 minutes out 

 of an hour in Area Sj passing into the area about 30 times o 

 Successive periods of time spent in Area Q varied ftom 20 

 seconds to 3 minutes o 



Ihe effect of continuous sound of 100 cycles per second 

 was first tested. The yellowfin spent 10 minutes out of the 

 hour in Area S^ entering it 26 times o 



Daring the hom-, the noise of the exhaust of a boat was 

 picked up fairly loudly by the hydrophone^ Most of the sound 

 doubtless entered the area from the seaward or west end through 

 the screened gates o Ihe fish remained in Area S for a much 

 longer time during this period of disturbanceo It also re= 

 entered the area after being away for but 20 to U5 seconds o 



If the period of disturbance is discounted, the fish 

 remained in Area S for about 6 minutes out of 55 minutes^ a 

 result which does not differ greatly from that of control 

 conditions,, Although there was no good evidence that the 

 yellowfin reacted to sound of 100 cycles per second, there is 

 the sijggestion that it might have been attracted by the complex 

 sound coming from the exhaust of the boato 



The effect of continuous sound of 200 cycles per second 

 was next tested^ Ihe tuna spent about 17 out of hi minutes in 

 Area S, and entered the area 18 times,, Ihe results are included 

 in table 10 j alu:.fi with those under control conditions ^ both 

 to illustrate the reactions, and to show the type of data which 

 were taken o 



For some unknown reason, the yellowfin became interested 

 in the hydrophone^ it swam up to it six times and appesn-ed to 

 exounine it closelyo It also circled in the area between the 

 transducer and the seaward end of the pondo Its sudden inter- 

 est m the hydrophone was peculiar, as it- had been swimming 

 past it, without any reaction, for the previous 3 hours,, 

 There is the possibility that the yellowfin might have been 

 attr'acted by a sound generated by the rubber cable rubbing on 

 itself or its support,, A strong gusty wind prevailed during 

 this part of the experiment, and although the cable was not 

 observed to move with the wind, it may have done sOo On the 



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