smaller surface fish captured to the north by 

 POFI vessels were, for the most part, not 

 represented in the size range of these deep- 

 swimming albacore. Of the 41 fish, 26. 8 per - 

 cent were 81-90 cm. in length, 41.5 percent 

 were 91-100 cm., 17.1 percent were 101-110 

 cnn. , and 14.6 percent were 111-120 cm. A 

 sinnilar size contrast was noted between the 

 Gilbert's troll aind longline catches during the 

 fall (fig. 4). 



During all cruises albacore brought on 

 deck in a viable condition were tagged and 

 returned to the sea (the number tagged, by 

 cruise, is shown in table 19, Appendix); thus 

 there were few data available on the sexual 

 development of the fish. All fish examined were 

 immature, and their gonads had not developed 

 sufficiently for the sexes to be distinguished 

 accurately in the field. 



DISTRIBUTIONS OF OTHER FISHES 



The seasonal shift in distribution and 

 presumably in abundance noted for the albacore 

 was also apparent in certain oth e r species. 

 Table 3 summarizes the northern seasonal limits 

 at which other fishes were taken within the 140 "W. 

 and 150°W. longitudes. This area was chosen 

 as a basis for comparison because it w a s the 

 one most extensively surveyed during the 1955 

 cruises (see figs. 1, 2, and 3). 



Bigeye tuna, Parathunnus sibi (Temminck 

 and Schlegel), taken on longline gear, showed a 

 progressive shift of their northern limit from 

 approximately 31 "N. in the spring to 37''N. in 

 the fall. Although inclement weather during the 

 fall cruise prevented an exact determination, 

 the northward limit of bigeye along 145° W. longi- 

 tude was somewhere between 37°38'N. and 

 46°07'N. latitude. An unusual concentration of 

 bigeye was discovered during the spring cruise 

 of the Smith . Fifty-five fish were captured with 

 longline gear between 36''43'N. , 143°42'W. and 

 25°14'N. , 148°10'W. In this area a large school 



of tuna was observed, at a depth of 5 to 10 

 fathoms, following the boat and apparently feed- 

 ing on the discarded longline baits. The school 

 was identified by the field party as bigeye tuna. 

 To the west of this catch the Manning (cruise 25) 

 took bigeye in similar latitudes but in smaller 

 numbers. 



Skipjack tuna, Katsuwonus pelamis 

 (Linnaeus), taken by both surface trolling and 

 longlining, were not abundant in the catches. 

 The catch data (table 3) showed a seasonal 

 progression northward in their distribution 

 from spring through fall. None was taken 

 within longitudes 140°W. and 150°W. during 

 the summer. To the east of this area they 

 were found at approximately 38*40'N., 

 132°16'W. and to the west at approximately 

 43°23'N. , 157°24'W, A single large school 

 was observed at about 23''28'N., 159*40'W. 

 during the fall cruise of the Gilbert . The 

 school was composed of large 18- to 25-pound 

 "season" fish. 



Only a single yellowfin tuna, Neothunnus 

 macropterus (Temminck and S c h 1 e g e 1 ) , was 

 captured on longline throughout these several 

 cruises and it was taken during the spring. 

 During the sumnier a large school of yellowfin 

 was sighted on the surface at 35''40'N. latitude, 

 172°36'W. longitude, by a fisherman on the 

 Smith (cruise 30). 



Two fishes, the great blue shark, 

 Prionace glauca (Linnaeus) and the lancet fish, 

 Alepisaurus sp. , showed a similar distinct 

 seasonal shift in their distributions. As indi- 

 cated by the catch rate, their numbers increased 

 progressively northward from spring through fall. 



The distribution of dolphin, Coryphaena 

 hippurus (Linnaeus), appeared to shift south- 

 ward during the fall. The evidence maybe 

 erroneous, however, since it was obtained 

 under poor sampling conditions experienced 

 during stormy weather on the northern portion 

 of the eastern leg, along 145°W. longitude, of 



Table 3. --Northern seasonal limits of tunas other than albacore and 

 certain other fishes, within 140°W. and ISCW, longitude 



— Northern limits of largest catch of a single day 



7 



