130 



Fishery Bulletin 94(1). 1996 



to 70 cm individuals was about 34 cm-yr -1 . The slopes 

 corresponding to those growth rates, when plotted 

 against the growth curve of the present study, show 

 close agreement (Fig. 10). These comparisons dem- 

 onstrate that 1) the microincrements on otoliths are 

 deposited on a daily basis and 2) the ages of young 

 tuna (FL <100 cm) estimated from otoliths are correct. 



Comparative study of yellowfin tuna 

 growths 



The growth curve obtained for yellowfin tuna from 

 the western Indian Ocean is similar to those obtained 

 by different investigators in other oceans and using 

 other age estimation methods. The use of skeletal 



2.5 



2 



L.5 



I ii 



0.5 



= u.o 



3.0 



2 ll 



I II 



mi 



□ Q D 



&* a 



B 



•£:'&{* .TO&^>£ ' 



30 



■in 



120 



150 



III 



60 



'Hi 



120 



150 



Fork length (cm) 



Figure 8 



Relationships between different measurements on the transverse sec 

 tion of yellowfin tuna, Thunnus albacares, otoliths and fish length. The 

 location of Dl and D2 are shown in Figure 3, where D = Dl + D2. 



Table 2 



Estimated parameters of the growth models for yellowfin tuna, Thunnus albacares, (all sexes, /; = 151i in the western Indian 

 Ocean (FL in cm, t in years). Est. = estimated value; SE = standard error. 



Est. 

 SE 



272.7 

 28.9 



0.176 

 0.027 



-0.266 

 0.050 



165.7 

 5.2 



2.1.31 



ii n:;:> 



0.629 

 0.033 



160.8 

 13.1 



II I, 'IS 



0.204 



1.450 

 5.269 



6.675 

 19.604 



