The Japanese Atlantic Longline Fishery, 1964, 

 and the Status of the Yellowfin Tuna Stocks 



By 



JOHN P. WISE, Fishery Biologist 



Bureau of Commercial Fisheries Tropical Atlantic Biological Laboratory 



Miami, Florida 33149 



ABSTRACT 



The Japanese Atlantic longline fishery increased in 1964 to nearly 85 million 

 hooks. Catches of yellowfin tuna decreased slightly, while catches of albacore in- 

 creased markedly. Even though fishing has decreased since 1964, the effort is still 

 greater than necessary for optimum yield in numbers of yellow-fin tuna. 



Wise and Le Guen (in press) reviewed the 

 Japanese Atlantic longline fishery from its 

 inception in 1956 through 1963. The fishery 

 began on a commercial scale in 1957, when 

 over 3 million hooks were set; by 1963 the 

 number of hooks had increased to more than 

 55 million. The principal species caught, 

 accounting for some 95 percent of the catch in 

 numbers, were yellowfin tuna, 1 albacore, big- 

 eye tuna, and blue marlin, in that order. 



They divided the Atlantic Ocean into 10 areas 

 (fig. 1): 



FLA Florida 



NOW North Oceanic (West) 



NOE North Oceanic (East) 



CV Cape Verde 



CAR Caribbean 



GUI Guiana s 



GG Gulf of Guinea 



BAH Bahia 



BEN Benguela 



RIO Rio de Janeiro 



Catch and effort statistics were analyzed 

 separately for each species in each area. 

 Three of the four principal species showed 

 declines in apparent abundance. Catch rates 

 of yellowfin tuna were declining by 1963 in 8 

 of the 10 areas. Declines in catch rates for 

 albacore, generally less than declines for 

 yellowfin tuna, occurred in three areas of the 

 western and central Atlantic. Bigeye tuna 

 showed little or no decline, but blue marlin 

 catch rates declined in three areas, two of 

 which were off the coast of South America. 



Common names only are given in theoriginaljapanese 

 reports. 



Catch rates for blue marlin tended to be an 

 order of magnitude lower than those for the 

 principal species, whereas the catch rates for 

 all other tunas and billfishes were much lower 

 even than those of the blue marlin. 



When they compared concentrations of fish- 

 ing effort with catch rates, they concluded that 

 the fishery was directed at yellowfin tuna and 

 albacore, and that the other species were 

 caught incidentally. 



Since the completion of Wise and Le Guen's 

 study, the Research Division of the Fisheries 

 Agency of Japan has published statistics on the 

 1964 fishery (Fisheries Agency of Japan, 1967). 

 Extensive tables showing numbers of hooks 

 used and catch in numbers by species, month, 

 and 5 square for 1964 cover the activities of 

 about two-thirds of the Japanese Atlantic fleet. 

 Of the 329 trips by conventional longliners, 216 

 (65 percent) are included; 62 (68 percent) of 

 the 91 trips by mother ships with skiffs are 

 covered. (There appears to be no significant 

 difference in catches or catch rates between 

 the two types of fishing.) 



As in the previous work, I have assumed that 

 the part of the fleet included in the logs 

 available for tabulation is representative of the 

 effort, catch, and geographical distribution of 

 the whole fleet. 



Some major changes took place in the fishery 

 in 1964; they are especially evident in the 

 following comparison of percentage changes 

 from 1963 to 1964 (table 1): 



Fishing effort +54% 



Yellowfin tuna catch - 1% 



Albacore catch +88% 



Bigeye tuna catch +21% 



Blue marlin catch -13% 



