NUMBER CAUGHT PER SCHOOL 



oi-s- 

 6r-r- 



WEIGHT CAUGHT PER SCHOOL 



OL-*- 



lOi-r- 





 100 



50 



1 1 ] ] \ T 1 \ \ 1 



NUMBER OF MEN FISHING PER SCHOOL 



FISHING DURATION PER SCHOOL 



1 1 1 1 T 



AVERAGE SIZE 



100 



50 



m 



■ 



NUMBER OF SCHOOLS 



m m 



VTA V/A rrr^ r777\ rr-\ I — | 



"I 2 3 4 5 6 7 8 9 10 I I 12 13 14 15 >I5 

 BAIT USED PER SCHOOL (BUCKET) 



Figure 7. — Relation between amount of bait used 

 per school and average values of catch per 

 school, number of men fishing per school, fish- 

 ing duration per school, and size of fish per 

 school, June-August 1967. 



vessels used from 9.0 to 22.6 buckets per trip. 

 Fully loaded, most vessels carry at least 36 

 buckets of bait, and sometimes much more, 

 per trip. 



A vessel with a full load of bait can fish 2-3 

 days, provided the bait does not die or is not 

 used up rapidly because of good fishing. That 

 chummers generally used bait sparingly is re- 

 flected in the data in table 7, which shows that 

 among nonresponding schools, the vessels 

 chummed 93 percent with only one bucket and 

 the remainder usually with two to five buckets 

 of bait. Even among responding schools, the 

 vessels fished 75 percent with up to only five 

 buckets of bait (table 7 and fig. 7). The average 



amount of bait used per school, by vessel, 

 ranged from 2.1 to 5.0 buckets per school. 

 Collectively, the average was 3.0 buckets per 

 school (table 3). 



Figure 7 shows the averages of the catch per 

 school, number of men fishing, fishing duration, 

 and fish size, plotted by the amount of bait used 

 per school. To show the mutual relationship 

 between the variables examined, we calculated 

 and tested the correlation coefficients, using a 

 hypothesis of p = 0. We found all the correla- 

 tion coefficients differing significantly from the 

 hypothesis (table 8). We concluded that the 

 amount of bait used, therefore, contributed 

 significantly to the average number and weight 

 of fish caught per school. It is also evident 

 that on schools requiring more bait, the aver- 

 age fish size was larger and fishing duration 

 longer. Usually, more men fished those schools 

 that required more bait. 



To measure the fleet's efficiency in the pro- 

 duction of skipjack tuna relative to the bait 

 supply, two indices are occasionally used-- 

 catch per bucket of bait caught and catch per 

 bucket of bait used (Yamashita, 1958; Brock 

 and Uchida, 1968). Because we did not collect 

 data for all baiting and fishing operations, we 

 could not calculate the catch per bucket of bait 

 caught; instead, we calculated the catch per 



Table 8. — The correlation coefficients calcu- 

 lated for the relation between bait used, men 

 fishing, fishing duration, and fish size and 

 the averages per school, of the number and 

 weight of fish caught, amount of bait used, 

 men fishing, fishing duration, and fish size. 

 A single asterisk denotes probabilities be- 

 tween 0.05 and 0.01; two asterisks denote 

 probabilities equal to or less than 0.01 



Components 

 of catch 



Bait used 



Men 

 fishing 



Fishing 

 duration 



Fish size 



Number 











caught 



0.744** 



0.956** 



0.979** 



-0.456 



Weight 











caught 



0.939** 



0.940** 



0.960** 



0.852** 



Bait 











used 





0.977** 



0.946** 



0.813** 



Men 











fishing 



0.899** 





0.753** 



0.300 



Fishing 











duration 



0,934** 



0.822** 





0.592* 



Fish 











size 



0.510* 



0.705 



0.847** 





Degrees of 

 freedom 



13 



6 



10 



10 



12 



