FISHERY BULLETIN: VOL. 70, NO. 1 



Figure 1. — Schematic diagram of cement tank used for tuna schooling studies. Insert 

 shows true dimensions of octagonal channels formed by acetate partitions. Rectangular 

 sidearms were divided in half lengthwise by the Plexiglas partitions, not shown here. 

 Center rectangle was used as a catwalk. 



1962) permit the fish to remain in the water from 

 the time of capture until release into tanks on 

 shore. 



The experiments were done in a large cement 

 tank that consisted of several differently shaped 

 compartments (Figure 1). An octagonal area 

 at one end was attached by moveable gates (not 

 shown in figure) to rectangular sections at the 

 other end. With the gates up the fish could be 

 transferred to one or the other section without 

 renetting for each experiment. Two concentric 

 octagons of transparent acetate formed three 

 separate swimming compartments for the ex- 

 perimental studies in the octagonal area; in 

 the rectangular areas, rigid, 6.3 mm thick, 

 transparent Plexiglas formed the partitions. 

 The more flexible acetate permitted some hydro- 

 dynamic transfer, but the rigid Plexiglas did 



not. In one series of tests with the Plexiglas 

 partitions, circular holes, 1.25 cm in diameter, 

 were evenly spaced about every 15 cm along the 

 partition. 



Films were taken from observation booths at 

 the ends of the sidearms and above the ceiling, 

 over the octagonal area. A 16 mm Bolex was 

 operated at 16 frames per second; a 10 mm 

 Kern-Paillard Switar or a 5.7 mm wide-angle 

 Kinoptic Tegea lens was used. Single frame 

 analysis of selected sequences provided data for 

 quantitative study (L-W Inc. Photo Optical Data 

 Analyzer, Model 224 A, Van Nuys, Calif.). At 

 the film speeds used, it was satisfactory to 

 measure every fifth frame, since positions 

 changed minimally during this time interval. 

 The number of frames given in the tables should 



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