YOSHIDA: AMERICAN SAMOA LONGLINE FISHERY 



the catch per trip. The data do indeed show that 

 the mean number of days fished per trip has 

 increased during recent years (Table 2). The 

 increase in the mean number of days fished per 

 trip may also, in part, indicate change in the size of 

 the vessels. That is, larger vessels, w^hich 

 presumably have larger fish-holding capacities, 

 probably fish more days to obtain a full load of fish. 



Table 2.-Total trip length, days spent fishing, and traveling 

 time per trip by longline vessels based at American Samoa. 



Mean number of days 



Year 



Total trip 

 length 



Fishing time 

 per trip 



Traveling time 

 per trip 



1963 

 1964 

 1965 

 1966 

 1967 

 1968 

 1969 

 1970 

 1971 



42.35 

 41.26 

 48.79 

 50.58 

 62.13 

 68.02 

 67.34 

 70.74 

 84.16 



26.12 

 27.39 

 32.09 

 33.74 

 38.03 

 43.20 

 44.25 

 45.03 

 52.03 



16.23 

 13.87 

 16.60 

 17.05 

 23.50 

 24.82 

 23.08 

 25.72 

 32.13 



In their analysis of the apparent abundance of 

 albacore from 1954 to 1965, Otsu and Sumida (1968) 

 indicated that the mean catch per trip increased 

 from 1954 through 1960 and then fell slightly and 

 stabilized at a lower level in 1963-64. A continua- 

 tion of this analysis (Figure 1) showed that the 

 mean catch per trip continued to fluctuate around 

 this lower level with no definite upward or down- 

 ward trend. It is possible that the mean catch per 

 trip is fluctuating near the mean fish-holding 

 capacity of the vessels or near a level that is relat- 

 ed to the profitability of the fishing trip. That is, a 

 vessel may fish as many days as are needed to 

 obtain a full load or until a catch that is at least 

 profitable is obtained. The trip, as an index of ef- 

 fort, does not take this factor into consideration, 

 and, therefore, the catch per trip is not an accurate 

 indicator of the apparent abundance. 



It would be useful then, to compare the catch per 

 trip with the catch per day, which is not affected 

 by as many variables as the catch per trip. The 

 mean annual catch per trip from 1959 to 1971 fluc- 

 tuated between 29.9 and 38.2 metric tons (Figure 

 2) and, as noted earlier, did not reveal any obvious 

 trends. The mean annual catch per day during the 

 same period fluctuated between 0.7 and 1.7 metric 

 tons, and, contrary to the catch per trip, declined 

 after 1962 suggesting that the longline vessels are 

 fishing more days to compensate for the reduced 

 catch per day. The mean total length of a fishing 





Z 



s 



s 

 a 



in 



z 

 o 



tn 



3 

 O 



< 



3 

 Z 

 Z 

 < 



"1 — \ — I — r 



MEAN CATCH /TRIP 



T — I — I — I — I — I — I — r 



3 



o 



1954 



1958 



1962 



1966 



1970 



Figure 1. -Total number of fishing trips, mean catch of albacore 

 per trip, and annual albacore landings, 1954-71. 



z 

 o 



< 



UJ 



s 



"1 1 r 



CATCH /TRIP 



CATCH/ DAY 



in 



z 

 o 



I960 1962 1964 1966 1968 1970 



Figure 2.-Comparison of the mean catch per day and mean 

 catch per trip of albacore, 1959-71. 



trip, number of days spent fishing, and number of 

 days spent traveling on each trip (Table 2) all 

 showed an increasing trend from 1963 to 1971, 

 which indicates that, in general, the vessels are 

 traveling farther away from the home base to fish 

 and are fishing more days per trip. 



749 



