SPAWNING OF ALBACORE IN THE SOUTH PACIFIC OCEAN 



159 



turc of fish near spawning condition or by the 

 collection and identification of fertilized ova or 

 larvae, we can only conjecture that albacore in 

 the South Pacific spawn over an extended area 

 north of 20° S. latitude. The data indicated no 

 apparent diflferences in size between albacore 

 found in the area north of 20° S. latitude and those 

 found south of 20° S. latitude (fig. 10). Fish 

 smaller than 86 cm., and presumably sexually im- 

 mature, were sampled in both areas, although 

 they were very few. It appears that adult fish are 

 distributed over the entire range of our sampling, 

 but that their seasonal movements are such that 

 spawning occurs largely in the more northern 

 area. 



Perhaps most significant in our findings is that 

 the albacore in tLe South Pacific Ocean spawn 

 during the southern summer months, in contrast 

 to the northern summer-spawning of the North 

 Pacific albacore (Ueyanagi, 1957; Otsu and 

 Uchida, 1959b). This difference in spawning sea- 



sons constitutes some evidence that the South 

 Pacific and North Pacific albacore stocks are in- 

 dependent of each other. Tag recoveries have 

 indicated that the three albacore fisheries in the 

 temperate North Pacific Ocean, conducted by the 

 Japanese off their coastal waters in spring, by 

 Americans off the Pacific coast of the United 

 States in summer, and by the Japanese in mid- 

 ocean during the winter months, are exploiting a 

 single population (Otsu, 1960). There is some 

 evidence that fish occurring within the North 

 Equatorial Current are the reproductive segment 

 of the same North Pacific population (Ueyanagi, 

 1957). What is not known at present is the rela- 

 tion of these fish to those occurring in the Southern 

 Hemisphere, and presently being fished by Japa- 

 nese and South Korean longliners in midocean and 

 by Chilean fishermen in their coastal fishery. 

 Pending more definitive results from further tag- 

 ging, our data suggest that an independent popu- 

 lation exists on each side of the Equator, and that 



Z 40 — 



EQUATOR - eCS 



N= 1353 



I FEMALES 

 MALES 



J I L 



m 



ao's-so-s 



N =419 



J I L-d ll I I 



|j u ll \mM 1. 



ii Mi-Hi ni m ^\ 



FORK LENGTH IN CENTIMETERS 



Figure 10. — A comparison of the sizes of albacore taken between the Equator and 20° S. and those between 20° S. and 



:50° S. latitude (by sex). 



