

\ 35 





36 





37 



38 



39 





40 





3 



\ (3.0) 



















-50' 





















\ 46 





45 





44 



43 



42 





41 



N. 



-29' 





















1 ""^ 



/ 93 

 ( (11.6) 





48 



8 

 (8.0) 





49 



50 



51 





52 



-28' 

























57/ 

 7 / 



^7.0) / 



43 



56 



55 



54^ 





53 



-27' 





























58 



59 



6 



1 (6.0) 



60 







-26' 



KANEOHE 



BAY 















NAUTICAL 



MILE 







\T ^ 



61 









1/2 













10 ] 

 (10.0) J 







25' 



26» 



IS-^-sr 50' 



49' 



4 



1 





7' 46 

 1 





\5i 



o 55' 55' 



54* 



53' 



s'a' 



KEEHI LAGOON 



NAUTICAL MILE 







/64^ 









20'- 







1/2 1 





/^3 



43 

 (21.5) 



540^ 

 (10.6), ^ 



65 





98 

 M7.5) 



N. 



19'- 



18' 



71 





69 



236 

 (15.9) 



68 Y 



19 

 (6.3) 







S6l 

 \l82C 



(7.6)? 



72 



73 



74 



75 



67 / 





Figure 



4. — Total 



catch 



and 



(in 



parentheses) 



catch per set, by statistical areas, of night 

 bait caught in Kaneohe Bay and Keehi Lagoon by 

 seven Hawaiian skipjack tuna fishing vessels, 

 June-August 1967. 



vessels from baiting at night at Pearl Harbor, 

 the only other leeward baiting ground with any 

 significant bait production. In 108 sets at Keehi 

 Lagoon, the vessels caught 1,118 buckets or an 

 average of 10,4 buckets per set (table 1). Fig- 

 ure 4 shows that areas 64 and 69 were highly 

 productive night-baiting grounds. 



The only other night-baiting ground of any 

 importance was Kaneohe Bay. In 18 sets, the 

 total catch reached 70 buckets or an average of 

 9.4 buckets per set (table 1). Like day baiting, 

 night baiting was most productive in area 47 off 

 Waiahole. The vessels spent only three nights 

 catching bait from other baiting areas. 



Collectively, in 117 nights of baiting, 129 

 sets produced 1,312 buckets of bait. Obviously, 

 a few vessels made more than one set per night 

 as evidenced by the difference in the number of 

 nights baited and number of sets made. We 

 calculated catch per set at 10.2 buckets , where- 

 as catch per night reached 11.2 buckets. Fre- 

 quently, catches of bait at night were insuffi- 

 cient for a day's fishing and the vessel spent 

 additional time baiting during the day. 



In night baiting, loss of bait through handling 

 was minimal and amounted to less than 1 per- 

 cent for all vessels over the 3-month period. 

 Excess bait, which was released or shared with 

 other vessels, amounted to about 1 percent of 

 the total catch, 



THE FISHING TRIP 



The fishing trip starts only after sufficient 

 bait is aboard to justify fishing. To be on the 

 fishing grounds by sunrise, the fishermen usu- 

 ally restrict traveling to darkness, when they 

 neither scout nor fish. From data on time of 

 departure and return to port, we found that 

 most trips originated between 0200 and 0600, 

 with 41 percent originating at 0501-0600 (table 

 2). The vessels usually returned to port be- 

 tween 1800 and 2200, although there were a few 

 trips that ended earlier or much later. Trips 

 ending at 2001-2100 were most frequent (17 

 percent), but there were almost as many trips 

 that ended at 1901-2000 (16 percent). By taking 

 the difference in time between the length of the 

 trip and the time expended in scouting and fish- 

 ing, we calculated that traveling time on 231 

 trips averaged 4.8 hours or about 31 percent of 

 an average trip of 15.5 hours. The average 

 traveling time of individual vessels ranged 

 widely from 3.6 to 6.5 hours per trip. 



A fishing trip of a Hawaiian skipjack tuna 

 vessel usually lasts 1 day, and has been used 

 as the unit of effort in past studies on apparent 

 abundance (Yamashita, 1958; Shippen, 1961; 

 Uchida, 1966, 1967), In the section that follows, 

 we discuss scouting, fishing, and catch per trip. 



Scouting 



Scouting, which averaged 9.7 hours or 62 

 percent of the time on an average fishing trip, 

 is an essential part in fishing surface schools 

 of tuna with either pole and line or purse seine 

 and, therefore, is a major component of effort 

 expended to catch fish. Usually, scouting, 

 started at daybreak; in 51 percent of the trips 



6 



