HIGH FREQUENCY TRANSDUCER 

 PIEZO- ELECTRIC CRYSTAL, 12 KC. TO 70 KC. 



15 MIN.-45.000 C.RS. 



ps; 



I 843 I 



29 



128 



15 MIN. CONTROL 



48 



457 150 162 95 99 



37 



15 MIN.- 50.000 C.RS. 



12 



50 



FOLLOWING TEST NO. 50 SEVERAL EXPERIMENTAL SIGNALS 

 WERE TRIED COVERING THE RANGE 12 KC. TO 70 KC. NO 

 MEASURABLE OR DISCERNIBLE REACTIONS WERE NOTED. 



FOR THE FOLLOWING TESTS THE SOUND WAVES WERE 

 BEAMED ACROSS PEN NO. 2 TO ACT AS A BARRIER OR 

 FENCE 



Figure 16.--Distribution of fish in pens, experiments 47-50. All experiments started with 1,000 fish in pen 

 No. 1 (far left). In controls, gates between pens lifted for indicated period, then lowered. Tests, same except 

 sounds of indicated durations and frequencies (cycles per second) applied at indicated location while gates 

 up. Numbers and dark bars show distribution of fish after gates lowered. 



15 



