446 



Fishery Bulletin 94(3). 1996 



formed after about age 4, the dark translucent zones 

 are narrow and only apparent in the region immedi- 

 ately adjacent to the annuli. The broad opaque zones 

 in the outer portions of the otolith section are sepa- 

 rate and distinct from the narrow opaque annuli, 

 which are still visible at higher magnifications (30- 

 50x) within the translucent zones in older fish, espe- 

 cially along the ventral ridge of the sulcus acusticus 

 and the ventral margin of the otolith section. 



We examined OTC-marked otoliths from five bone- 

 fish ranging from 465 to 661 mm in length and from 

 4 to 18 years in age (Table 1). All otoliths showed the 

 expected pattern of otolith growth; one annulus had 

 been formed per year. Marginal-increment analysis 

 of otoliths also suggested that one annulus had been 

 formed during March-June each year (Fig. 3). Me- 

 dian marginal increments had a consistent seasonal 

 minimum during April— June and a maximum in 

 October-February from 1992 to 1994. When median 

 marginal increments were plotted for individual age 

 classes 4—9, a similar pattern was seen (Fig. 4). 



Of 471 otoliths processed for age estimation, only 

 20 (4.2%) were rejected because of disagreements 

 among readings. The length-frequency distribution 

 offish whose otoliths were rejected because they were 

 unsuitable for age estimation was not significantly 



different from that of all fish whose otoliths were 

 examined (Kolmogorov-Smirnov two-sample test, 

 D=0.234, P=0.22 ). The oldest bonefish examined were 

 a 650-mm female estimated to be 19 years old and a 

 641-mm male also estimated to be 19 years old (Table 

 3). Bonefish growth was rapid until an age of about 

 6 years and then slowed considerably (Fig. 5). Re- 

 sults of likelihood-ratio tests showed a significant 

 difference in the overall von Bertalanffy growth mod- 

 els for males and females <x 2 =26.15, df=3, P<0.001, 

 Table 4). Estimates of Lj x 2 =0.406, df=l, P=0.52), K 

 (Z 2 =1.54, df=l, P=0.21), and t <x 2 =1.28, df=l, P=0.26) 

 were not significantly different between sexes. 

 Lengths at age predicted by the von Bertalanffy equa- 

 tion agreed with the observed lengths of both female 

 and male bonefish (Fig. 5). Predicted lengths at age 

 of females were greater than those of males for all 

 ages greater than 1 year, and observed lengths at 

 age of females were greater than those of males for 

 all ages except 1 and 18 (Table 3). The age-frequency 

 distributions of males and females were significantly 

 different (Kolmogorov-Smirnov two-sample test, 

 D=0.265, P<0.001); females (median age=7 yr, 

 interquartile range=4 yr, n=262) in our sample were 

 significantly older than males (median age=6 yr, 

 interquartile range=4 yr, n=181; Mann- Whitney [/-test, 



