flocks showed 700 (56 percent) consisted of 50 

 or more birds, 458 (37 percent) had 11-50 

 birds, and 91 (7 percent) had 10 or fewer birds. 

 Tabulating only those schools chummed, by 

 size of the flock, we tested the ratios of the 

 number of schools with catches to those with- 

 out and found them differing significantly 

 ( x^= 66.60; d.f. = 2; p < 0.01). Table 19 shows 

 that of 617 schools with catches, most had 50 

 or more birds (68 percent), whereas of 437 

 schools without catches, most had only 11-50 

 birds (47 percent). Actually, of 607 schools 

 associated with 50 or more birds, 7 out of 10 

 schools yielded catches. 



Catch Per Trip 



The amount of fish caught per school influ- 

 ences the catch per trip, which has been 

 tabulated by weight of fish in table 20. The 



distribution of catch per trip was skewed and 

 in 244 trips, of which 22 or 9 percent ended in 

 zero catches, most had 0.1-1.0 metric ton. 

 Actually, slightly more than half (55 percent) 

 of the catches were 3.0 metric tons or less per 

 trip. Vessel F, the low producer among the 

 vessels, averaged 2.0 metric tons per trip, 

 whereas vessel A, the high producer, averaged 

 twice as much or 4.1 metric tons (table 3). 

 The grand mean was 2.8 metric tons or about 

 376 fish per trip. 



Strongly skewed toward small catches, the 

 distribution of catch per school in table 21 

 shows that the vessel usually caught between 

 0.1 and 0.5 metric ton or between 1 and 100 

 fish. Actually, catches ranged from 1 kg, to 

 9.0 metric tons or from 1 to 1,710 fish, and 

 averaged 1.1 metric tons or 148 fish, slightly 

 higher than the positions of the modes in the 



Table 19. — Number and percentage of 617 schools with catches and 437 schools without 

 catches, fished by seven Hawaiian skipjack tuna fishing vessels and tabulated by 

 size of bird flocks associated with the schools at the time of fishing, June-August 

 1967 



Size of bird flock 



Schools 



With catches 



Without catches 



Total 



Number 



Number 



Percent 



Number 



Percent 



Number 



Percent 



10 or fewer 



11 to 50 

 50 or more 



26 

 172 

 419 



4.2 

 27.9 

 67.9 



42 

 207 

 188 



9.6 

 47.4 

 43.0 



68 

 379 

 607 



6.4 

 36.0 

 57.6 



Table 20. — Number of trips, schools, catch per trip, catch per school, and number 

 of schools fished per trip, tabulated by the weight of fish caught per trip by 

 seven Hawaiian skipjack tuna vessels, June-August 1967 



Size of catch 



Trips 



Schools 



Catch per trip 



Catch 



per school 



Schools per tri 



Metric ton 



Number 



Number 



Number 



Number 



Metric ton 



Number 







22 













0.1-1.0 



53 



103 



130.6 



67.2 



0.3 



1.9 



1.1-2.0 



41 



113 



256.3 



93.0 



0.6 



2.8 



2.1-3.0 



41 



131 



503.8 



157.7 



0.8 



3.2 



3.1-4.0 



26 



71 



512.2 



187.6 



1.3 



2.7 



4.1-5.0 



23 



73 



514.9 



162.2 



1.4 



3.2 



5.1-6.0 



12 



36 



847.2 



282.4 



1.9 



3.0 



6.1-7.0 



12 



45 



638.3 



170.2 



1.8 



3.8 



7.1-8.0 



6 



18 



659.0 



219.7 



2.5 



3.0 



8.1-9.0 



4 



18 



830.3 



184.5 



1.9 



4.5 



9.1-10.0 



1 



6 



865.0 



144.2 



1.6 



6.0 



10.1-11.0 



2 



6 



1,002.5 



334.2 



3.6 



3.0 



11.1-12.0 















12.1-13.0 



1 



3 



1,015.0 



338.3 



4.1 



3.0 



22 



1 



