15 MIN- 45,000 C.RS. 



51 



354 S39S 44 



563 



52 



15 MIN. SIREN, 20,000 TO 50,000 C.RS 



T ^ *-— 1 ^~ 1 " ^ I — — 1 



53 



4 =?4I=: 167 



133 



58 



50 



102 



68 



81 



296 



54 



15 MIN. CONTROL 



55 



15 



56 



MIN. -60^00 



C.RS. 



481 =j42= 



II 



III 



97 



75 



87 



72 



24 



Figure 17. --Distribution of fish in pens, experiments 51-56. Experiments 51-53, 55, 56 started with 1,000 

 fish in pen No. 1 (far left); 54 started with 1,000 fish in pen No. 10 (far right). 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. 



17 



