FISHERY BULLETIN: VOL. 73, NO. 4 



changes in cannery operating procedures, changes 

 in the sampling procedures were necessitated in 

 subsequent years. The collection of sex and weight 

 data was discontinued in early 1971. Catch and 

 effort data have been provided voluntarily by the 

 fishing vessel operators from about 75% of the 

 fishing trips. 



The longliners on some occasions fish widely 

 scattered areas on a single fishing voyage. Since 

 there is no way to determine the origin of each fish 

 in the catch and because the fish are sampled at 

 random at the docks, it is probable that some 

 samples included fish from several different loca- 

 tions. This problem was minimized by summariz- 

 ing the length data by large geographical areas. 



ANNUAL LANDINGS OF ALBACORE 

 AND YELLOWFIN TUNA 



Except for dips in 1961 and 1964, the albacore 

 landings increased steadily from 1954 to 1965 (Ot- 

 su and Sumida 1968). In the 6 yr that followed, the 

 landings fluctuated between 17,722 and 28,310 

 metric tons (Table 1). 



The gain in importance of yellowfin tuna can be 

 seen in the increased landings in the later years 

 (Table 1). After a period (1954 to 1964) of reported 

 landings of less than 2,500 metric tons, the 

 reported landings increased substantially and 

 fluctuated between 4,514 and 8,567 metric tons 

 from 1965 to 1971. 



APPARENT ABUNDANCE OF 

 ALBACORE AND YELLOWFIN TUNA 



Otsu and Sumida (1968) used various indices of 

 apparent abundance in discussing the status of the 

 fishery for albacore during 1954 to 1965. These 

 indices included catch per trip, catch per day, and 

 catch per 100 hooks. However, because data on 

 number of hooks fished per day were not available 

 for the entire period of their study, they elected to 

 use the fishing trip as the basic measure of effort 

 in analyzing the apparent abundance of albacore. 

 They also examined the relation between catch 

 and effort, and CPUE (catch per unit of effort) 

 and effort, in evaluating the effect of fishing on 

 the stock. 



Ideally, in considering the mean annual CPUE 

 as an index of apparent abundance, the fishery 

 should affect all portions of the stock(s) under 

 consideration equally throughout the years. 



Table L-Total annual albacore and yellowfin tuna landings in 

 American Samoa, 1954-71. 



However, since the geographical limits of the 

 fishery have been expanding each year, the situa- 

 tion is almost certainly not ideal. In this section I 

 will extend some of the analyses of Otsu and 

 Sumida to determine if any changes have occurred 

 in the apparent abundance of albacore from 1966 

 to 1971. Since there are now 9 yr of effort data in 

 terms of the number of hooks fished, I will make 

 greater use of the catch per 100 hooks to determine 

 the apparent abundance of albacore. It is assumed 

 that fishing efficiency is not influenced by the na- 

 tionality of the vessels, for Skillman (1975) found 

 no evidence to suggest that any gear modification 

 or change in the nationality of the fleet has caused 

 any change in the catchability coefficient of al- 

 bacore in the Samoan fishery. 



Apparent Abundance of Albacore 



Otsu and Sumida (1968) analyzed the mean an- 

 nual CPUE of albacore from 1954 to 1965 in terms 

 of the catch per trip. They believed that the catch 

 per trip was a satisfactory measure of apparent 

 abundance because their analysis showed a close 

 relationship between the monthly average catch 

 per trip and the monthly average catch per day. 

 However, there are some basic shortcomings in the 

 catch per trip. One is that the catch per trip of any 

 vessel is limited by its fish-holding capacity. Also, 

 as indicated by Otsu and Sumida (1968), the catch 

 per trip is influenced by changes in the number of 

 days fished per trip and by changes in the size 

 composition of the vessels in the fleet. Changes in 

 the number of hooks fished per day can also affect 



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