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I I I I I I I I I I I I 



5 10 15 20 25 30 35 40 45 50 55 60 



TIME (MINUTES) 



Figure 6. — Frequency of pursuit time and chum- 

 ming time per school for seven Hawaiian skipjack 

 tuna fishing vessels, June-August 1967. 



Chumming starts as soon as the vessel 

 crosses the head of the school and if the fish 

 start to bite, the chummer throws more bait 

 to bring the school near the stern so fishing 

 can start. If there is no response, chumming 

 stops temporarily, marking the completion of a 

 "pass." Usually, then, the vessel is swung 

 around for another pass. We defined chumming 

 time as the interval from the start of chum- 

 ming to the landing of the first fish and calcu- 

 lated it only for those schools with catches 

 because we did not record the time that a non- 

 responsive school was abandoned. 



The distribution of chumming time, which 

 varied from less than a minute to 141 minutes, 

 was strongly skewed; chumming lasted less 

 than a minute in 4 percent of the schools, 1-5 

 minutes in 58 percent, 6-10 minutes in 13 per- 

 cent, and 11 minutes or more in 25 percent 

 (table 5 and fig. 6). Chumming time, which 

 varied widely, reflects the biting behavior of 

 schools; some bit readily, whereas others re- 

 sponded slowly. Vessel F chummed an average 

 of only 4.6 minutes per school, the least among 

 the vessels; it probably abandoned nonrespon- 

 sive schools early (table 3). Vessel E chummed 

 the longest, spending an average of 13.2 min- 



utes per school before catching any fish. 

 Chumming time of all vessels averaged 9.4 

 minutes per school. 



We estimated that collectively on 231 trips 

 the vessels chummed 1,036 schools out of 1,249 

 schools sighted or about 83 percent. Table 4 

 and figure 5 show that the distribution of trips, 

 tabulated by the number of schools chummed, 

 was moderately skewed, that the number of 

 schools chummed per trip ranged from 1 to 16, 

 and that trips on which the vessels chummed 

 three or four schools were most frequent. 

 Reference to individual vessels showed that the 

 percentage of schools chummed varied widely 

 from 66 percent for vessel C to 97 percent for 

 vessel G, which incidentally chummed 5.4 

 schools per trip, the highest average among 

 the vessels. Vessels B and C, both with the 

 lowest rates, averaged 3.8 schools per trip. 

 The grand mean was 4.5 schools per trip 

 (table 3), 



Sometimes, a vessel will pass up a school or 

 abandon one even before catching fish. There 

 were 653 schools which were not fished for 

 reasons given in table 6. About half of the 

 schools did not respond to chum and were 

 abandoned, 28 percent sounded or moved too 

 fast to overtake, 18 percent were composed of 

 fish too small for canning or marketing, and 

 4 percent were passed up so that the vessels 

 could fish other schools. 



Table 6. — Number and percentage of 653 schools 

 not fished by the seven Hawaiian skipjack tuna 

 fishing vessels, tabulated by their reasons 

 for abandoning the schools, June-August 1967 



Reasons for not fishing 



Schools 



Number Percent 



Chummed but no response 322 49.3 



School sounded or moving too fast 182 27.9 

 Fish too small 120 18.4 



Chummed another school close by 29 4.4 



Fishing 



In fishing skipjack tuna schools with pole and 

 line and live bait, the vessels usually fish only 

 a few minutes and catch a variable fraction of 

 the fish from each school. Fishing time per 

 trip, the sum of the time spent fishing each 

 school, averaged 68 minutes (1.1 hours), which 

 is only about 7 percent of the average trip 

 time. There was, however, a wide variation — 



10 



