S0NDJFMAMJJA50NDJFMAMJJAS0NDJFMAMJJAS0ND 



J I . I I " I 



1962 



I9fe3 



1964 



1965 



FiQUBE 16. — Monthly mean lengths of albacore landed at 

 American Samoa, September 1962 to December 1965. 



fishery of an abundant year class or by a general 

 decrease in the abundance of the older, larger fish 

 in the stock. To determine if either of these factors 

 might contribute to the decrease in mean length 



during February-April, we shall examine the size 

 data in more detail. 



DIFFERENCES IN FISH SIZE BY LATITUDE AND 

 LONGITUDE 



The mean length of albacore taken within 

 5-degree latitudinal bands (fig. 17) tends to in- 

 crease from north to south. The fish are smallest 

 near the Equator and largest at lat. 20° to 25° S. 

 Albacore tend to be small again south of 25° S. 

 These results are in general agreement with the 

 findings of Honma and Kamimura* (1957), al- 

 though in contrast to these workers, we did not 

 observe any significant increase in the size of alba- 

 core to the north of lat. 10° S. with the exception 

 of 1963. 



No longitudinal trend is noticeable. Honma and 

 Kamimura found a general tendency for the size 

 of albacore to increase from west to east. These 

 authors, however, examined data from the western 

 South Pacific between long. 140° E. and 170° W., 



1962 



1963 



1964 



1965 



u 



i 



! 



LL^yi I 



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I II III III III 



NORTH 6° S ll°S 16° S 2I°S 26° S NORTH 6° S ll°S I6°S 2I°S 26° S 

 OF I I I I I OF I I I I I 



5°S 10° S 15° S 20° S 25° S 30° S 5° S 10° S 15° S 20° S 25° S 30° S 



LATITUDE 



LATITUDE 



NORTH 6° S ll°S I6°S 2I°S 26° S NORTH 6°S ll°S I6°S 21° S 26° S 



OF I I I I I OF I I I I I 



5°S 10° S 15° S 20° S 25° S 30° S 5° S 10° S 15° S 20° S 25° S 30° S 



LATITUDE LATITUDE 



Figure 17. — Annual mean lengths of albacore (.sexes combined) taken by the American Samoa-based vessels, by 



latitudes, 1962-65. 



M 



U.S. FISH AND WILDLIFE SERVICE 



