duction in the proportion of males has acted to 

 amplify the general size decrease. This influence 

 was reflected in the decreased catch per 100 hooks 

 (by weight) during these months (fig. 9). 



SUMMARY 



1. This report is based on (a) data on landings 

 provided by the two tuna packing firms operating 

 in American Samoa, (b) catch and effort data pro- 

 vided liy the operators of American Samoa -based 

 fishing vessels, (c) size and sex data on albacore 

 sampled at the tuna canneries in American Samoa, 

 and (d) Japanese data made available to us by the 

 Japan Fisheries Agency. 



2. Tlie tuna fishery based in American Samoa 

 l)egan in 1954 with a fleet of seven Japanese long- 

 line vessels. The fleet grew rapidly and in 1965, 154 

 vessels fished out of American Samoa. The com- 

 position of the fishing fleet, in terms of country of 

 origin of the vessels, has changed. In tlie early 

 years of the fishery, the fleet was composed entirely 

 of longliners from Japan. The 105-vessel fleet op- 

 erating during the last quarter of 1965 was com- 

 posed of 62 vessels from Japan, 30 from the Re- 

 public of Korea, and 13 from the Republic of 

 China. 



3. The fishei-y was confined to the immediate 

 vicinity of the Samoa Islands in the early years, 

 but has expanded rapidly to the east and south. 

 In 1965, the fishery area was bounded on the north 

 by the Equator, on the south by lat. 30° S., on 

 the west by long. 175° E., and on the east by about 

 long. 120° AV. These boundaries enclose an area of 

 about 23 million square kilometei-s. 



4. Tliough a variety of pelagic fishes is taken 

 by the longline fishery, albacore command the 

 highest price at the canneries and are, for this rea- 

 son, fislied for selectively. Data provided by the 

 fishermen are complete only with respect to the 

 albacore catches, the major species taken. Conse- 

 quently, no attempt was made in this report to 

 analyze the data on the other tuna species. 



5. The annual landings of albacore in American 

 Samoa have gradually increased from 338 metric 

 tons in 1954 to 15,588 metric tons in 1965. 



6. The occurrence of albacore in the South Pa- 

 cific Ocean exhibits no clear seasonality although 

 in most years landings have been slightly better 

 during the latter half of the year. 



7. The catch of albacore per fishing trip was 

 used as tlie measure of apparent abundance for 



68 



the entire period of the fishery's existence. No other 

 unit of efi^ort was available before 1959 when data 

 first were recorded on number of days fished per 

 trip and 1963 when we began to collect data on 

 number of hooks fished per day. This index proved 

 to be reasonably satisfactory, however, because 

 neither the average number of days fished per trip 

 nor the size composition of the vessels has varied 

 appreciably over the years covered by our study. 



8. The catch per trip (in terms of weight of 

 fish) tends to increase with size of vessel, mainly 

 because (1) larger vessels generally fish more gear 

 than smaller vessels, and (2) their trips tend to 

 be longer. However, the fact that relatively few 

 vessels in the American Samoa fleet were larger 

 than 120 tons or smaller than SO tons iiermits the 

 use of catch per trip as an index of apparent 

 abundance. 



9. The catch per trip tended to increase steadily 

 through 1960, tapered ofl', and stabilized at a lower 

 level in 1963 and 1964. There was again a slight 

 increase in 1965. 



10. Annual landings have tended to be directly 

 proportional to the total amount of fishing effort. 



11. The size of the vessel does not significantly 

 atfect the catch rate in terms of catch per 100 hooks 

 fished. 



12. The distriljution of albacore is continuous 

 from west to east in tlie South Pacific Ocean, at 

 least between long. 140° E. and 90° W. The fish 

 have their greatest abundance, however, in the 

 central and eastern South Pacific Ocean between 

 180° and 120° W. 



13. During the first half of the year, the Ameri- 

 can Samoa-based vessels generally fish north of lat. 

 20° S., where catches are most favorable. In later 

 months, beginning alx)ut June or July, the albacore 

 longline fishery moves southward to as far as lat. 

 30° S. 



14. The number of albacore caught per 100 hooks 

 did not vary appreciably in 196.3-65. But owing to 

 tlie decrease in average size of albacore caught, 

 the weight of fish landed per 100 hooks declined 

 significantly in 1964 and early 1965. 



15. The mean lengths of albacore landed in 

 American Samoa did not change significantly from 

 September 1962 to January 1964, but suddenly be- 

 came smaller in February 1964. Although the mean 

 length increased slightly after May, the fish re- 

 mained smaller than in 1962-63. The average 



U.S. FISH AND WILDLIFE SERVICE 



