1954 1955 1956 1957 1958 1959 I960 1961 1962 1963 1964 1965 



FiGUBE 4. — Total annual albapore and yellowfin tuna 

 landings in American Samoa, 1954-65. 



c-eding year were registei-ed. Although yellow&i 

 tuna was the dominant species hmded in 1954 and 

 in parts of 1955 and 1956, the albacore has domi- 

 nated the catch since 1957. 



Albacore are taken throughout the year (fig. 5) . 

 In most years for which we have data, slightly 

 better landings have been made during the latter 

 half of the year. In some years (e.g., 1961, 1963, 

 1964), however, no seasonal trend is evident. 



APPARENT ABUNDANCE OF ALBACORE 



Various indices of apparent abundanc* of alba- 

 core are examined in the following sections. These 

 include catch per trip, catch jier day, and catch 

 per 100 hooks fished. 



CATCH PER TRIP AS A MEASURE OF APPARENT 

 ABUNDANCE 



The apparent abundance of tunas taken by a 

 longline fishery is generally measured by the catch 

 per 100 hooks fished. We did not, however, begin 

 to collect information on the number of days fished 

 l^er trip until 1959 and did not begin to collect 

 data on the number of hooks fished per day until 

 1963. We were compelled, therefore, to use the 

 fishing trip itself as the unit of effort to indicate 

 trends in apparent abundance of albacore for the 

 entire period of existence of the American Samoa- 

 ba,sed fishery. 



Admittedly, the catch per trip is an inexact 

 measure of apparent abundance because it is great- 

 ly influenced by changes in number of days fished 



FMAMJJASOND 

 MONTHS 



JFMAMJJASOND 

 MONTHS 



FiGUBE .0. — The monthly catch of albacore, in percentages 

 of annual total, by American Samoa-based vessels, 1954-6.5. 



per trip and by size composition of vessels in the 

 fleet. The average number of days fished per trip 

 by the American Samoa-based vessels has, how- 

 ever, remained relatively steady from year to year, 

 at least between 1959 and 1964 (fig. 6) . As we show 

 later, size composition of vessels also changed little 

 during the entire 1954-65 period. Furthermore, 

 the close relation between the monthly average 

 catch per trip and the monthly average catch per 

 day fished, assuming that catch per day is a more 

 reliable index (fig. 7), indicates that the catch 

 per trip is a satisfactory measure of apparent 

 abundance. 



ALBACORE TAKEN IN LONGLINE FISHERY IN AMERICAN SAMOA 



51 



