EARLY LIFE HISTORY AND SPAWNING OF THE ALBACORE, THUNNUS 



ALALUNGA, IN HAWAIIAN WATERS 



BY HOWARD O. YOSHIDA, Fishery Biologist 



BUREAU OF COMMERCIAL FISHERIES BIOLOGICAL LABORATORY 



HONOLULU, Hawaii %812 



Thirty-five juvenile albacore were found in the 

 stomachs of 4,568 billfishes captured in Hawaiian waters 

 between July 1962 and April 1966. 



Regressions of standard length on lengths of various 

 segments of the vertebral column, determined from 

 measurements made on 21 intact specimens caught 

 in the Pacific Ocean, were used to estimate the lengths 

 of the fragmentary specimens. A linear regression 



ABSTRACT 



was used to describe the first year's growth of albacore. 

 By use of the regression, expected lengths for various 

 ages, in days, up to I year were obtained. One-year-old 

 albacore were estimated to be 38 cm. in standard 

 length. The spawning season for albacore in Hawaiian 

 waters peaks in May and probably extends from March 

 to September. 



The albacore (Thunnus alahinga) in the North 

 Pacific are believed to constitute a single sub- 

 population, the adults of which sujjport fisheries 

 oft' the coasts of North America and Japan. The 

 age and growth of adult albacore have been esti- 

 mated and hypotheses have been developed on 

 their migrations among the fisheries (Otsu, 1960; 

 Clemens, 1961; Otsu and Uchida, 1963). 



Basic information on young albacore before 

 (hey are recruited into the commercial fisheries 

 is sketchy, however. Descriptions of larval alba- 

 core appear in the literature, but they need verifi- 

 cation. Matsumoto's (1962) description of larval 

 albacore difl'ers significantly from that of Yabe 

 and Ueyanagi (1962). Yabe, Ueyanagi, Kikawa, 

 and Watanabe (1958) and Yoshida (1965) pub- 

 lished descriptions of the anatomy of juvenile al- 

 bacore, and Asano (1964) published observations 

 on the morphology. The present report treats as- 

 pects of the early life history of albacore before 

 their recruitment into the commercial fisheries. 

 Growth in the first year of life is estimated and in- 

 ferences are made on the spawning habits of the 

 adults. 



The juvenile albacore for this study came from 

 the stomachs of billfishes, which are good collec- 



Published October 1968. 



FISHERY BULLETIN; VOL. 67, NO. 2 



tors of juvenile tunas (Yabe et al., 1958; Yoshida, 

 1965). The Honolulu fish markets were an excel- 

 lent source of billfishes from which stomachs could 

 be sampled with relatively little difficulty. Al- 

 though the abundance of billfishes varied season- 

 ally, stomachs were available from every month in 

 a 46-m()nth period between 1962 and 1966. The 

 billfish stomachs yielded 35 juvenile albacore. 

 Skipjack tuna (Rdfuuwonus pchimia), the most 

 numerous ju\'enile tuna, was aliout 24 times more 

 numerous than albacore. Smaller numbers of ju- 

 venile yellowfin tuna {T. albacares), bigeye tuna 

 {T. ohcm(s), and other tunas and tunalike fishes 

 were found. 



COLLECTION AND EXAMINATION 

 OF STOMACHS 



Stomachs of 4,568 billfishes were examined from 

 July 1962 to April 1966—3,751 .striped marlin 

 {Tetniptvni.'i aiuhix), 477 blue nuirlin {Makaira 

 n'igncan.<i), 268 shortbill sjwarfish {Tetraptums 

 angustirostris) , 34 black marlin {Makaira indka), 

 31 sailfish {Istiophonis orientaU.s), and 7 unidenti- 

 fied billfishes. The .stomachs of .striped marlin, blue 

 marlin, and shortbill spearfish contained juvenile 

 albacore. 



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