894 



Fishery Bulletin 97(4), 1999 



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Figure 2 



Scanning electron micrographs o? Coryphacna Jiippurus sagittal otoliths. (A) Ridges on the surface of the central 

 area of the otolith (scale bar=155 jjm): (Bl thin increments laid down in the central region of the otolith, showing 

 rhythmic growth patterns of 7- and 14-increment groupings (scale bar=35 urn); iC) wider increments laid down in 

 the outer region of the otolith (scale bar=10 urn i; iDi rhythmic growth pattern of 14 daily growth increments (scale 

 bar=15 /imi. 



71=1) to 20.6-23.9 mm (at day 36, «=3). In general, 

 poorly defined concentric increments, consisting of 

 an adjacent dark and a light zone, were laid down 

 around the core (Fig. IE). In relation between age in 

 days and number of increments, neither the .r-axis 

 intercept nor the slope were significantly different 

 from and 1, respectively (^test;P>0.05):y = 0.3894 

 + 0.9846.r (;!=75, /•=0.98). 



From the juvenile fish, 125 otoliths were read 

 (71%), 73 females between 19.5 and 58.5 cm FL and 

 52 males between 16.5 and 58 cm FL. Observed mini- 

 mum and maximum ages were 47 and 176 daily 

 growth increments. Of 36 adult fish otoliths studied 

 with the light mici-oscope, only 15 (42% ) were able to 

 be interpreted. A high percentage were rejected ow- 

 ing to error in reading precision greater than 5% or 

 to erosion of the marginal zone during the polishing 



process. In specimens between 67 and 117 cm FL, 

 the minimum and maximum ages read were 189 and 

 362 daily growth increments, respectively. 



Scales from 139 adult specimens, measuring 65- 

 124 cm FL, could be interpreted (93% ). The results 

 showed the presence of three age groups within the 

 population: 67 1-yr-old specimens ranging from 65 

 to 110 cm FL( -t =87.95, SD=10.15), 61 2-yr-oIds mea- 

 suring 73-120 cm FL ( .v =97.54, SD=10.95) and 11 

 3-yr-olds measuring 92-124 cm FL (.v=108.73, 

 SD=10.17). 



The von Bertalanffy growth function was calcu- 

 lated on the basis of the age-length relationships 

 from daily growth rings in juvenile otoliths and 

 annulaein adult scales (Fig. 4). Adult daily ages were 

 not taken into account in these calculations because 

 of observed underestimations in aging adults from 



