SEXUAL MATURITY AND SPAWNING OF ALBACORE IN THE CENTRAL 



SOUTH PACIFIC OCEAN 



By Tamio Otsu, Fishery Research Biologist, and Richard J. Hansen, Bureau of Commercial Fisheries Biological 



Laboratory, Honolulu, Hawaii 



The albacoro tuna, Thunnus germo (Lacepedc), 

 is found generally throughout temperate and 

 tropical waters of the Pacific Ocean, where it is 

 the basis of important fisheries for Americans and 

 Japanese. The demand in America for canned 

 albacore has steadily increased, and today this 

 demand is met only by a considerable importation 

 of frozen and canned fish. The Japanese, at 

 present the principal suppliers of albacore, fish for 

 this species along with other tunas in the tropical 

 Indian and Atlantic Oceans as well as in the 

 Pacific (Otsu, 1959). 



As part of the research of the staff of the Bureau 

 of Commercial Fisheries Biological Laboratory 

 (Honolulu) a study was initiated in August 1957 

 of the gonadal development and spawning of 

 albacore in the South Pacific Ocean. Such a 

 study had previously been conducted on North 

 Pacific albacore (Otsu and Uchida, 1959b). Pres- 

 ently it is not known whether the albacore fished 

 by Americans and Japanese in the temperate 

 North Pacific Ocean belong to the same popula- 

 tion as those of the South Pacific. This study 

 was undertaken to obtain (1) a broader under- 

 standing of the biology of the albacore and (2) 

 a possible clue to the relation between fish occur- 

 ring in the Nortli and South Pacific Oceans. 



Tag recoveries have shown that the albacore of 

 the temperate North Pacific make oceanwide 

 migrations and probably constitute a single inter- 

 mingling population exploited by both Americans 

 and Japanese (Ganssle and Clemens, 1953; Blunt, 

 1954; Otsu and Uchida, 1959a; Otsu, 1960). It 

 is also known from previous studies that albacore 

 do not spawn in temperate waters of the North 

 Pacific (Otsu and Uchida, 1959b). There are 

 indications that adult fish move south from tem- 

 perate waters to spawn in subtropical waters, 

 possibly to the west of, and in the general latitudes 

 of, the Hawaiian Islands (Ueyanagi, 1957; Otsu 



Note.— Ai>iiiovi'<i for jiulilicalinn .\iig. 7, 1961. ri.shciy Hullctin 2(14. 



and Uchida, 1959b). It is necessary to obtain 

 similar information for albacore in the South 

 Pacific before anj- stud}' can be made of the total 

 population structure of this important tuna 

 resource. 



The authors wish to acknowledge the excellent 

 cooperation extended by the management and 

 staff of the Van Camp Sea Food Co., in making 

 this study possible. Donald Doran, former gen- 

 eral manager, and his staff at the Van Camp Tuna 

 Company cannery in American Samoa were in- 

 strumental in getting the gonad sampling accom- 

 plished. Mort Miles and Francis Yuhashi helped 

 in many ways with the collecting, preserving, and 

 shipping of samples. Poulima Tumanuvao and 

 John Williams, Samoan cannery employees, faith- 

 fully sampled daily landings, made accurate length 

 and weight measurements on the sampled fish, 

 and kept excellent records which formed the basis 

 of this stud}'. 



SOURCE OF MATERIALS 



The tuna fishery based in American Samoa 

 offers an excellent source of materials for the 

 study of albacore spawning in the South Pacific 

 Ocean. Albacore are landed throughout the J'ear, 

 making it possible to obtain samples continuously 

 for the study of seasonal variation in gonad 

 development. Furthermore, the great extent of 

 the area fished makes possible the study of areal 

 variations in spawning activity. 



An account of the beguining of this tuna fishery 

 is given by Van Campen (1954). At present 

 (I960), the cannery in Pago Pago, American 

 Sainoa, is being served by a fleet ol about 35 

 Japanese and 3 Korean longline fishing vessels. 

 From its l)egiiiniiig in 1954, with a fleet of 7 

 boats and an albacore production of 270 tons, tlie 

 fishery has continued to expand, until landings 

 of albacore today exceed 12,000 short tons (fig. 1). 



151 



