Sadovy et al Age and growth of Epinephelus gunatus in Puerto Rico and St Thomas 5^9 



Validation 



Marginal increment analysis Mean marginal incre- 

 ments for Puerto Rico fish were plotted on a monthly 

 basis for annuli I-VI individually, and combined for 

 annuli VII-X because of low monthly sample sizes for 

 these older age-groups (Fig. 3). These data indicate 

 that, at least for annuli II-V, the opaque zone begins 

 to form between about April and May and is a true 

 annulus. For annulus VI, the zone is laid down later, 

 between May and July. For annuli VII-X combined, 

 opaque zones are apparently deposited annually be- 

 tween May and July. 



Since sample sizes from St. Thomas were too low for 

 marginal increment analysis by individual age-group, 

 otoliths from all age-groups were combined and plotted 

 on a monthly basis by the percent of sections that 

 lacked a marginal increment. These data indicate that 

 the time of opaque zone formation (i.e., spring/summer) 

 is similar for both Puerto Rico and St. Thomas (Fig. 

 4). A possible 'pseudoannulus' was detected in 74 (12%) 

 of sectioned otoliths. This was a wide, weakly -discern- 

 ible band always located between the focus and the first 

 annulus. It occurred sporadically in fish of all sizes. 



Field validation study Of a total of 139 fish tagged, 

 injected, and released, 8 females from age-classes 1-4 

 were recaptured 5-16 months following tagging. Mean 

 monthly growth rates for recaptured individuals from 

 Puerto Rico measured 1-8 mm (Table 1). One individual 

 (#00038) was recaptured in February 1991, 18km from 

 the tagging site on an offshore bank, a known spawn- 



a. 



100 



80 



60 



40 



20 



SONDJ FMAMJ JA 

 Month 



Figure 4 



Percentage of otolith sections lacking a marginal in- 

 crement for Epinephelus guttatus from Puerto Rico 

 (solid line) and St. Thomas (dashed line) for age groups 

 1-10. 



