v7x\mmUm\m\Am. 



SCHOOLS SIGHTED 



N= 1,249 



EL 



1 



SCHOOLS CHUMMED 



N = 1,036 



gzil Leza. 



SCHOOLS SUCCESSFULLY FISHED 



1 N = 587 



I 2 3 4 5 6 7 8 9 10 n 12 13 14 15 16 17 18 

 SCHOOLS PER TRIP (NUMBERS) 



Figure 5. — Percentage frequency of trips tabu- 

 lated by the number of schools sighted, chummed, 

 and successfully fished per trip by seven Hawai- 

 ian skipjack, tuna fishing vessels, June-August 

 1967. 



out of five trips, that from one to five sightings 

 were reported on more than half of the trips 

 (57 percent), and that 18 schools were the most 

 sighted on one trip. 



When a flock is sighted, the vessel pursues 

 it in an attempt to head off the school and begin 

 chumming. The interval between sighting and 

 the Start of chumming, which we called pursuit 

 time, varied widely among the vessels. Con- 

 sidered an integral part of scouting time be- 

 cause scouting continues even when the vessel 

 is pursuing a school, pursuit time is obviously 

 influenced by the vessel's speed and its dis- 

 tance from the school at the time of sighting. 

 Some elements, however, prolong pursuit time; 

 for example, when schools are scarce on the 

 fishing grounds, a captain may feel compelled 

 to chase a nonbiting school longer than usual, 

 or to drift and wait up to an hour for schools 

 that have sounded to return to the surface. 



The frequency distribution of pursuit time, 

 tabulated by 5-minute intervals, was strongly 

 skewed toward short intervals (table 5 and fig. 

 6). Pursuit time ranged from 1 to 105 minutes, 

 but the mode in the distribution occurred at 6- 

 10 minutes. The vessels pursued about 80 per- 

 cent of the schools for 20 minutes or less, 15 

 percent from 21 to 40 minutes, and 5 percent 

 longer than 40 minutes. Among the vessels, 

 pursuit time averaged from 9.4 minutes for 

 vessel G to 31.5 minutes for vessel C with a 

 grand mean of 15.0 minutes (table 3). 



Table 5. — Number, percentage, and cumulative percentage frequencies of schools 

 pursued and chummed by seven Hawaiian skipjack tuna fishing vessels, tabu- 

 lated by pursuit and chumming time in 5-minute intervals, June-August 1967 



Time 



Pursuit time 



Chumming time 



Minute 



Number 



Percent 



Cumulative 

 percent 



Number 



Percent 



Cumulative 

 percent 



<1 









25 



4.1 



4.1 



1-5 



228 



22.2 



22.2 



357 



58.1 



62.2 



6-10 



254 



24.7 



46.9 



81 



13.2 



75.4 



11-15 



217 



21.1 



68.0 



47 



7.6 



83.0 



16-20 



117 



11.4 



79.4 



22 



3.6 



86.6 



21-25 



64 



6.2 



85.6 



22 



3.6 



90.2 



26-30 



56 



5.4 



91.0 



19 



3.1 



93.3 



31-35 



25 



2.4 



93.4 



9 



1.5 



94.8 



36-40 



10 



1.0 



94.4 



14 



2.3 



97.1 



41-45 



14 



1.4 



95.8 



5 



0.8 



97.9 



46-50 



7 



0.7 



96.5 



4 



0.6 



98.5 



51-55 



5 



0.5 



97.0 



1 



0.2 



98.7 



56-60 



9 



0.9 



97.9 









>60 



21 



2.1 



100.0 



8 



1.3 



100.0 



Totals 



1,027 







614 







9 



