124 



AbStf3Ct.— Microincrements of 

 otoliths of 151 yellowfin tuna, Thunnus 

 albacares, caught in the western Indian 

 Ocean by French and Mauritian purse 

 seiners were used to establish growth 

 curves. On the basis of comparisons 

 among several otolith preparations 

 ( transverse or oblique sections, acetate 

 replicas of the external face) and two 

 methods of examination (light micro- 

 scopy and scanning electron micro- 

 scopy), we chose to observe transverse 

 otolith sections in light microscopy to 

 estimate age in days. 



The von Bertalanffy growth curve, FL 

 = 272.7 ( 1 - e-° 176 " + ° 266 '), where FL = 

 fork length in cm and t in years, is very 

 similar to those obtained by other in- 

 vestigators. It does not support the hy- 

 pothesis that yellowfin tuna of the east- 

 ern Atlantic Ocean and the western In- 

 dian Ocean have two growth stanzas. 

 Back-calculated dates of spawning 

 show that yellowfin tuna spawn suc- 

 cessfully throughout the year, but prin- 

 cipally between November and March. 



Age and growth of yellowfin tuna, 

 Thunnus albacares, from the western 

 Indian Ocean, based on otolith 

 microstructure* 



Bernard Stequert** 



Belle W Baruch Institute for Marine Biology and Coastal Research 

 University of South Carolina, Columbia, South Carolina 29208 



Present address. Laboratoire de Sclerochronologie des Animaux Aquatiques, ORSTOM 

 B P 70, 29280 Plouzane, France 



Jacques Panfili 



Laboratoire de Sclerochronologie des Animaux Aquatiques, ORSTOM 

 B.P 70, 29280 Plouzane. France 



John Mark Dean 



Belle W Baruch Institute for Marine Biology and Coastal Research 

 University of South Carolina, Columbia. South Carolina 29208 



Manuscript accepted 14 September 1995 

 Fishery Bulletin 94:124-134 ( 1996). 



Numerous studies have been con- 

 ducted on the age and growth of 

 yellowfin tuna, Thunnus albacares, 

 in the tropical oceans using three 

 techniques: 1) length-frequency 

 analyses (Moore, 1951;Hennemuth, 

 1961; Davidoff, 1963; Le Guen and 

 Sakagawa, 1973; Marcille and 

 Stequert, 1976; Fonteneau, 1980; 

 Gascuel et al., 1992; Marsac 1 ); 2) 

 tagging (Bard, 1984; Bayliff, 1988); 

 and 3) observation and interpreta- 

 tion of marks on calcified structures 

 such as scales (Yabuta et al., 1960; 

 Huang et al., 1973), vertebrae 

 (Aikawa and Kato, 1938; Romanov 

 and Korotkova 2 ), dorsal spines 

 (Shabotiniets, 1968), or otoliths 

 (Wild and Foreman, 1980; Uchi- 

 yama and Struhsaker, 1981; Wild, 

 1986; Yamanaka 3 ). 



Only a few age and growth stud- 

 ies have been conducted in the In- 

 dian Ocean, and the results have 

 been contradictory. There are pres- 

 ently two hypotheses concerning 

 yellowfin tuna growth. The first 

 suggests that growth follows a von 



Bertalanffy model (von Bertalanffy, 

 1938), with growth rates from 2.9 

 to 3.4 cm per month for individuals 

 between 60 and 70 cm. These stud- 

 ies were based on the analysis of 

 length-frequency distributions 



' Contribution 1053 of the Belle W. Baruch 

 Institute for Marine Biology and Coastal 

 Research of the University of South Caro- 

 lina, Columbia, SC 29208. 



"To whom correspondence should be ad- 

 dressed 



1 Marsac, F. 1991. Growth of Indian 

 Ocean yellowfin tuna estimated from size 

 frequencies data collected on French purse 

 seiners. FAO, Indo-Pacif. Tuna Prog., 

 Workshop on stock assessment of yellow- 

 fin tuna in the Indian Ocean, Coll. Vol. of 

 Working Documents TWS/91/17, 8 p. 



2 Romanov, E. V., and L. P. Korotkova. 

 1988. Age and growth rates of the yel- 

 lowfin tuna (Thunnus albacares) (Bon- 

 naterre, 1788) (Pisces, Scombridae) in the 

 northern part of the Indian Ocean, deter- 

 mined bv counting the rings of vertebrae. 

 FAO, Indo-Pacif. Tuna Prog., Coll. Vol of 

 Working Documents TWS/88/38, p. 68-73. 



1 Yamanaka, K. L. 1990. Age, growth, 

 and spawning of yellowfin tuna in the 

 southern Philippines. FAO, Indo-Pacif. 

 Tuna Prog. Working Paper 90AVP/21, 87 p. 



