FISHERY BULLETIN! VOL. 69, NO. 4 



tern has been deduced for albacore in the North 

 Pacific. Otsu and Uchida (lOfsS) hypothesized 

 that the juveniles in the North Pacific migrate 

 from tropical and subtropical waters into tem- 

 perate waters and are recruited into the adult 

 population in higher latitudes, presumably north 

 of lat 30° N. Generally speaking, then, the al- 

 bacore in the North and South Pacific, which 

 are believed to constitute separate subpopula- 

 tions, follow similar migration patterns within 

 their respective hemispheres. The adults are 

 believed to spawn in lower latitudes, between the 

 equator and lat 20° where the eggs hatch and 

 the larvae develop into juveniles. The juveniles 

 then migrate into higher latitudes as they grow 

 and they join the adult population in the higher 

 latitudes. 



AGE AND GROWTH 



Information on age and growth is useful in 

 determining certain vital statistics for fish pop- 

 ulations and it would be useful if the growth 

 of juvenile albacore in the South Pacific could 

 be determined. Around Hawaii juveniles (60- 

 350 mm SL) were estimated to grow about 

 31 mm per month (Yoshida, 1968). It would 

 have been interesting to compare this growth 

 with that of juveniles in the South Pacific. A 

 plot of juvenile albacore length by time of cap- 

 ture, however, did not indicate that the length of 

 the juveniles was increasing with time. 



DISTRIBUTION AND ABUNDANCE 



Because the data for any one year were sparse, 

 the data for all years were combined to deter- 

 mine the quarterly distribution of juvenile al- 

 bacore (Figure 3). The apparent distribution 

 of juvenile albacore may reflect the operations 

 of the longline boats. The longline vessels based 

 at American Samoa primarily were seeking al- 

 bacore and selecting areas where albacore catch 

 rates tended to be high. The vessels generally 

 fished north of lat 20° S in the fir.st half of the 

 year and beginning in June or July moved south- 

 ward to as far south as lat 30° S (Otsu and 

 Sumida, 1968). The data indicated that the co- 

 operating vessels generally followed this pattern. 



In spite of this shortcoming the data suggest 

 some interesting features of the seasonal distri- 

 bution of juvenile albacore. 



In the first quarter billfish stomach samples 

 were collected between long 150° and 178° W 

 and lat 5° and 16° S. The juveniles were gen- 

 erally found throughout the sampling area west 

 of long 153° W. 



In the second quarter the longitudinal range of 

 sampling was slightly greater but the juveniles 

 were restricted to the west between long 165° and 

 179° W. Latitudinally, most of the stomach 

 samples were from north of lat 10° S except 

 for a few samples from about lat 31° S. Ju- 

 veniles were taken between lat 5° and 9° S and 

 at lat 31° S. 



In the third quarter stomach samples were 

 available from long 140° W to 178° E between 

 lat 5° and 31° S. The juveniles were absent in 

 samples from north of 14° S. 



In the fourth quarter the sampling area was 

 bounded by long 135° W and 178° E and lat 6° 

 and 21° S. Juveniles were absent from the east- 

 ermost portion of the area. They were taken 

 between long 157° and 179° W and lat 9° and 

 20° S. These observations suggest that the cen- 

 ter of the spawning area is closer to the area 

 between long 160° W and the 180th meridian 

 than farther to the east. 



Variations were also evident in the apparent 

 abundance of juvenile albacore as indicated by 

 the number of juveniles found monthly per 100 

 billfish stomachs (Figure 4). 



Juvenile albacore were found in all months 

 except July and August. Peaks in apparent 

 abundance occurred in January, April, and No- 

 vember. 



The data for all years were pooled because 

 billfish stomachs were unavailable for some 

 months in some years. Also, estimates of ap- 

 parent abundance may be biased by the small 

 sample sizes. The shortcoming of combining 

 data for all years and considering a large area 

 as an entity is that annual and areal variations 

 in apparent abundance are ob.scured. For ex- 

 ample, in 1965. except in April when four ju- 

 venile albacore were taken, no juveniles were 

 found in billfish stomachs from north of lat 10° S. 



The ovei'all abundance of juveniles was greater 



824 



