The yield of yellowfin tuna in 1964 was 

 657,000 fish for the yellowfin areas and 879,000 

 for the whole Atlantic. These catches (about 

 20 percent above equilibrium yields) were 

 obtained with fishing efforts respectively 375 

 percent and 567 percent above the estimated 

 optimum effort. 



If Le Guen and Wise's conclusions about 

 optimum effort and yield are reasonably accu- 

 rate, it is evident that the yellowfin tuna 

 fishery was conducted uneconomically from 

 1960 on, and in a manner which destined 

 catches and catch per unit effort to continue 

 to fall. A drastic reduction in fishing effort, 

 particularly in the six yellowfin tuna areas, 

 was indicated. 



Although the peak number of Japanese long- 

 liners, nearly 160, operating in the Atlantic 

 was passed in 1964, a sizable number of these 

 vessels continued to fish into 1965. By early 

 1966, however, the number had dropped to 

 about 75, and by the end of that year to 70. 

 From January through the first part of Septem- 

 ber 1967, only about 60 Japanese longliners 

 were fishing at any given time in the Atlantic, 

 and a substantial portion of the fishing was 

 in albacore areas. 



Thus, effort was reduced markedly from the 

 1964 level; if it continues low, some increase 

 in the catch of yellowfin tuna per unit effort 

 should be noticed for 1967. The increase in 

 1968 and 1969 should be greater, according 

 to Le Guen and Wise's observation that changes 

 in catch rates usually lag 2 to 3 years behind 

 changes in fishing effort. 



The fishing effort in 1967, however, was 

 still well above that indicated for optimum 

 yield in numbers of yellowfin tuna. In 1965-67, 

 longliners from other countries --notably Cuba, 

 Korea, and China (Taiwan)--entered the Atlan- 

 tic fishery, so that fishing effort has not 

 actually diminished as much as the Japanese 

 statistics would indicate. 



Analysis of the longline fishery for yellowfin 

 tuna is perhaps simplistic without reference to 

 longline fisheries for other species or to the 

 west African surface fishery which catches 

 substantial amounts of yellowfin tuna. Nonethe- 

 less, the fact is that only 30 longliners, each 

 with the fishing power of an average Japanese 

 longliner (about 2,000 hooks per day for an 

 estimated 250 days a year), would exert the 

 fishing pressure recommended by Le Guen 

 and Wise, 15 million hooks per year, for 

 optimum yield in numbers of yellowfin tuna. 



From 1956 to 1963 the albacore catch rate 

 declined in the Bahia, North Oceanic (East), 

 and Guianas areas (Wise and Le Guen, in press). 

 Table 4 of the present study shows that the 

 declines continued through 1964 at about the 

 same rates in the Bahia and Guianas areas, 



but unusually good fishing for albacore in the 

 North Oceanic (East) area made 1964 the best 

 year for the region. Significant declines ap- 

 peared for the first time in 1964, however, 

 in the Cape Verde and Gulf of Guinea areas. 



Wise and Le Guen reported that bigeye tuna 

 showed little or no decline in catch rates from 

 1956 through 1963; the same situation prevailed 

 through 1964. 



Catch rates of blue marlin showed declines 

 previously in the Bahia, Guianas, and North 

 Oceanic (West) areas. When the data are com- 

 bined for the 1956-64 period (table 5), these 

 areas continue to show declines in catch rates 

 comparable to the previous declines. Two more 

 areas, North Oceanic (East) and Cape Verde, 

 show declining catch rates for the first time. 



Rank correlation between fishing effort and 

 catch rates shows, as in previous years, that 

 the fishermen distributed their effort effi- 

 ciently with respect to the total catch and to 

 yellowfin tuna and albacore combined, but 

 inefficiently as to bigeye tuna and blue marlin. 

 For the first time, the correlation between 

 fishing effort and catch rate of yellowfin tuna 

 is negative and that between fishing effort and 

 albacore catch rate is positive. This relation 

 substantiates the conclusion that in 1964, the 

 Japanese longline fishery in the Atlantic be- 

 came primarily an albacore fishery, after 

 having evolved from a yellowfin tuna fishery to 

 a mixed yellowfin-albacore fishery. 



Table 5. --Catch rates and rates of decline for blue 

 marlin, Japanese Atlantic longline fishery, 1956-64 



1 Rate of decline calculated as slope of a straight 

 line (shown here as absolute value) fitted to logarithms 

 of monthly catch rates, beginning with the first month 

 of fishing in the best year. 



2 Highly significant (P = 0.01 or less). 



3 Significant (P = 0.05 or less). 



