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Fishery Bulletin 98(3) 



liths had an annulus on the edge. The greatest percentages 

 occurred during March-May of each year, confirming that 

 annuH are formed then (Fig. 4). A cyehc annual pattern 

 of margin deposition was consistent for common snook of 

 all ages: three inclusive groups, with data pooled sufficient 

 to reveal trends, showed a consistent annual cycle of nar- 

 rowest margins during March-May and widest margins 

 during late fall and early winter. By June, annulus forma- 

 tion was completed (Fig. 4). 



Of the 3883 sectioned otoliths that we examined, 369 

 (9.5% ) were rejected because of disagreements among read- 

 ings. The length-frequency distribution of fish whose oto- 

 liths were rejected because they were unsuitable for age 

 estimation was not significantly different from that offish 

 whose otoliths were readable (Kolmogorov-Smirnov two- 

 sample test, two-sided test statistic=1.344, P=0.054). 



Ages estimated from whole otoliths were significantly 

 less than those estimated from sectioned otoliths (paired 

 /-test, A=4.595, P<0.001), In addition, the slope of the 

 regression of whole-otolith annulus counts on sectioned- 

 otolith annulus counts was 0.873 (SE=0.014), which was 

 significantly less than 1 (/-test=8.75, P<0.001; Fig. 5). Dis- 

 crepancies between the ages estimated from the two struc- 

 tures were as great as five years, but usually the ages 

 determined from whole otoliths were underestimated by 

 1-2 years for fish older than 10 years. Ages determined 

 from the two structures agreed for 123 fish, whole-otolith- 

 derived ages were greater for 15 fish, and sectioned-oto- 

 lith-derived ages were greater for 72 fish. The oldest fish 

 aged from the sectioned otoliths was estimated to be 21 

 years old and the oldest fish aged from whole otoliths was 

 estimated to be 19 years old. 



