SONDJFMflMJJASONDJFMAMJJASONOJFMAMJJASOND 



1962 



1963 



1964 



1965 



FiGtiRE 19. — Estimated numbers of two size categories of 

 male albacore landed by the American Samoa^based fish- 

 ery, September 1962 to December 1965. 



dant year class. If so, we would expect that the 

 numbers of larger fish — those longer than 90 cm. — 

 would increase as this large year class moved 

 through the fishery. Such an increase is indicated 

 by the data. The abrupt increase in small fish in 

 February 1964 was followed by an increase in 

 larger fish toward the latter part of 1964. Near the 

 end of 1964 and in early 1965, an increase in the 

 number of small fish of both sexes was followed 

 by an increase in longer fish a few months later. 

 A large part of this change in size composition 

 is attributable to shifts of fishing grounds, as dis- 

 cussed previously. Year-class strength, however, is 



>90CM 

 <90CM 



I I I I i I I 1 I I I 



SONDJFMAMJJASON0JFMAMJJAS0N0.IFMAMJJA50ND 



^-J' , ^' , ^' , ' 



1962 1963 1964 1965 



FiGiTiE 20. — Estimated numbers of two size categories of 

 female albacore landed by the American Samoa-based 

 fishery, September 1962 to Decem,ber 1965. 



probably also an important contributor to the ap- 

 parent changeover in size composition during the 

 3-year period. Analysis of data from a few more 

 years would clarify this question. 



SEX RATIO OF ALBACORE 



Changes in sex ratio could also affect the size 

 composition of the landings since the monthly 

 mean lengths of male albacore are from 1 to 6 cm. 

 greater than those of females. 



The proportion of males in the total landings 

 (fig. 21) has fluctuated greatly without noticeable 

 trend over the years. On the other hand, the pro- 

 portion of males among the larger fish (>90 cm.) 

 increased through September 1964, after which it 

 tended to level out. 



Although males averaged around 62 percent of 

 the monthly landings between September 1962 and 

 December 1965, their percentage did decrease in 

 1964 and 1965 during periods corresponding to 

 months of reduced mean sizes (i.e., February-June 

 1964, February-August 1965). Though the mean 

 lengths of both sexes decreased simultaneously 

 during these months (fig. 16), the coincidental re- 



I I I I I I I M I I 





PERCENTAGE OF MALES 

 IN TOTAL LANDINGS 



PERCENTAGE OF MALES 

 IN FISH > 90 CM 



SONDJFMAMJJASONDJFMAMJJASONDJFMAMJJASOND 

 -^ I I . ^1 . > 1 ^ 1 



1962 



1964 



1965 



Figure 21. — Monthly sex ratio of albacore landed by the 

 American Samoa-based vessels. 



ALBACORE TAKEN IN LONGLINE FISHERY IN AMERICAN SAMOA 



67 



