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Fishery Bulletin 94(4), 1 996 



postovulatory follicles from preservation artifacts. 

 Because of the time between capture and preserva- 

 tion, significant amounts of atresia occurred. The atre- 

 sia limited the usefulness of the ovary sections because 

 postovulatory follicles could not be distinguished from 

 atretic conditions and histological materials. 



Gonadosomatic indices (GSI) were calculated from 

 the ovarian samples collected from New Caledonia 

 and Tonga by using the formula of Kume and Joseph 

 (1969): 



GSI = 10 4 W/L 3 , 



where W = total gonad weight in grams minus fatbody 

 and L = fork length in centimeters. The GSI was cal- 

 culated only for those females whose ovaries were 

 collected and processed in the laboratory. The criti- 

 cal GSI value was determined to be 1.7 according to 

 the definition of maturity by Cayre and Farrugio 

 (unpubl. data), 3 the value for which 100% of the fe- 

 males display an advanced mode of oocyte develop- 

 ment (>0.3 mm) (Fig. 3). 



Results 



Length-frequency distributions of sampled 

 albacore 



Length and sex data were collected on 1,105 alba- 

 core in the South Pacific. Size frequencies differed 

 between males and females in both the New 

 Caledonia and Tonga sites (Fig. 4, A and B). Male 

 albacore had two size modes, 8-91 cm FL and 100- 

 102 cm FL (Fig. 4, A and B). The relative strength of 

 the modes differed at each sampling site. Female al- 

 bacore from New Caledonia had a single mode, 86- 

 92 cm FL (Fig. 4A), whereas females from Tonga pos- 

 sibly displayed two size modes, 87-89 cm FL and 92- 

 96 cm FL (Fig. 4B). Few females over 100 cm FL were 

 collected in either the New Caledonia or Tonga 

 samples. 



Male albacore were encountered more often than 

 female albacore (Fig. 4, A and B). Male albacore ac- 

 counted for 68.9% of the samples from New Caledonia 

 and for 74.5% of the samples from Tonga (Table 1). 



3 Cayre, P., and H. Farrugio. 1983. Biologie de la reproduction 

 du listao Katsuwonus pelamis de l'Ocean Atlantique. Doc. SKJ. 

 Conf./83/12, presente a la reunion de cloture du Programme 

 International de Recherches sue le listro Atlantique, Teneriffe 

 (Espagne), juin 1983, 62 p. 



Oocyte development 



The most advanced stage of oocytes collected during 

 the austral winter months was the unyolked oocytes 



