the area is recorded by Bj, and the number of passes at one fupl or 

 the other (down) of the two lures is recorded by A„ Typical record^ 

 ings are shown in figure 19o 



In addition to the above „ the speed of the tunny was 

 determined in several trials under control and experinnental condi= 

 tions by timing the leader of the school as it passed through the 

 attraction area;, using a stop watcho 



RESPONSE UNDER CONTROL AND 

 EXPERIMENTAL CONDITIONS 



The pattern of activity of the fish was observed under 

 control and experimental conditions and is discussed below,, The 

 activity was measured quantitatively in several different waySp each 

 of which will be presented and discussed in the sections to followo 



Pattern of Response 



During control periods the tunnyj, usually in one school 

 or in two schools of unequal size;, swam slowly back and forth along 

 most of the length of the pond^ looping in deeper water near the ends^ 

 or often pausing to "play" m shallower water at the ends before 

 looping, 



A kymograph record of observations during a 15-minute 

 control period in one experiment is shown in figure 19Ao It is dis- 

 cussed in detail to illustrate the interpretation of the kymogramo 

 The first histogram shows that 22 seconds after the startp a school 

 of 12 tunny entered the field from the easto After spending 24 seconds 

 m the fieldp they left by the sime side as they came m^ and swam to 

 the eastern end of the pondo After 165 seconds the school returned 

 and swam through the field m 10 secondSf as shown by the second 

 histogramo The school looped in the western 1/lOth of the pond 

 during a 9-'Second interval and re-entered the area from the western 

 side. As shown by the third histogram, they sped through the field 

 in 8 secondSo After 147 seconds 'he schools re-entered the area 

 from the eastp stretched out in linear formation^ with the leader 

 entering the field about 6 seconds ahead of the 12*h funny (fourth 

 histogram! „ After leaving the fieldp the school spent 84 seconds in 

 the western 1/lOth of the pondj, during which time they circled in 

 the shallow southwestern corner near the pump. After passing 

 through the field for a fifth timei, the tunny stayed in the eastern part 

 of the pond for a long period- =about 4 minutes- before returning to 

 pass through the area fsixth histogram)o When they entered the area, 

 2 turned back, but 10 passed through to spend 60 seconds m the 



67 



