TO 10 90 100 110 120 



■■'UITCIS 



Figure 3. — Albacore sizes taken by various 

 kinds of fishing gear. 



tions, there is an alternate year shift in 

 the modal sizes in longline albacore and 

 our example happens to show the frequency 

 for a year when the modal size was small. 

 However, the important point of difference 

 between longline and live-bait albacore in 

 the North Pacific is the absence in the 

 latter of the largest fish (above 50 pounds) . 



The size is greater in the tropical 

 South Pacific. In Hawaii, although few fish 

 are taken, the sizes are generally larger 

 (60 to 70 pounds) . 



The gill net size frequency is based 

 on albacore taken by POFI in the central 

 North Pacific in the summer of 1956. The 

 trolling data were obtained from landings 

 made in Oregon during the 1958 season. 



Examples of yellowfin sizes are 

 given in three panels of figure U. Live- 

 bait catches on the U. S. west coast (data 

 obtained from Inter-American Tropical Tuna 

 Commission Bulletin 11(5): 215-217); troll 

 catches in the Line Islands; and longline 

 catches in the Line Islands. The latter 

 two panels were constructed from data pub- 

 lished by Iversen and Yoshida (1957, Special 

 Scientific Report — Fisheries No. 203), based 

 on work of the Honolulu laboratory. 



Perhaps it is important to point out 

 that yellowfin taken by longline throughout 

 the tropical and subtropical Pacific differ 

 widely in average size. Yellowfin from the 

 Hawaiian Islands are, on the whole, the 

 largest sampled to date, and there is also 

 a general increase in size from west to 

 east along the Equator in the Pacific. 

 Examination of Hawaiian yellowfin samples 

 showed that the mean size of the males is 

 greater than the mean size of females in 

 the dominant size groups sampled by long- 

 line. For example, in one year studied, 

 the dominant female modal group was centered 

 at about 120 pounds, and that of the male 

 at about 130 pounds. There is also an 

 unequal sex ratio among the larger fish in 

 favor of the males (as is the case with 

 albacore) . Hawaiian yellowfin range in 

 weight roughly between 50 and 290 pounds, 

 while the Line Islands sample shown in the 

 figure ranges upward to around 200 pounds. 



In summary, the tremendous expansion 

 of the Japanese tuna fisheries during recent 

 years has been based on their use of the 

 longline fishing method, which is an effec- 



3 



ft 



5 



U--i i i i—i 



*0 50 to 70 to fo 100 im 120 ISO 140 ISO ItO 



unem in cihtimctcis 



Figure 4. — Yellowfin sizes taken by various 

 kinds of fishing gear. 



14 



