46 



Fishery Bulletin 100(1) 



40 

 30 

 20 

 10 

 



40 

 30 

 20 

 10 

 



' " ^f^T^T^T 



August (n=522) 



September (n=491) 



40 



30 - 



20 - 



10 - 







I ' I ' I ' I 

 October (0=193) 



i MMM '!' i^T T -i T 



40 

 30 

 20 

 10 - 

 



November (n=772) 



r f M l l lf'T'T-T T T 



40 -1 

 30 

 20 

 10 

 



December (0=714) 



fiHIv 



40 

 30 

 20 

 10 

 



m- 



January (n=597) 



-T* 



M*i 



T-l^ 



40-] 

 30 - 

 20 

 10 

 



February (n=471) 



4llM^M- 



T-T '!■ 



40 -, 

 30 



20 - 

 10 

 



March (n=713) 



40 

 30 - 

 20- 

 10 







April (n = 587) 



m^^ 



40 

 30 

 20 

 10 - 

 



I ' I ' I ' I ' T^T'T'I ' I ' I 

 IVIay (n=430) 



I t MU ' I ^T I IT 



40 -J 

 30 - 

 20 - 

 10 

 



June (n=193) 



i MM 'f' H 'TT I T 



40 -| 



30 - 



20 - 



10 - 



-■ 



July 



No samples 



I ' I ' I ' I ' I ' I ' I ' I ' I ' I 



10 20 30 40 SO 60 70 80 90 100 



10 20 30 40 50 60 70 60 90 100 



Standard length (mm) 



Figure 4 



Pooled length-frequency histograms for Mayan cichlids collected with drop 

 traps from 1990 to 1996. 



and back-calculated length-at-age data for males (r'-=0.82, 

 n=581) and females (;'-^=0.77, /!=639). Our observed and 

 back-calculated size of age- 1 fish (mean ±1 standard er- 

 ror=45.5 ±10.11 mm, range=33-68 mm, ti=22} correspond- 

 ed well with the modal length of age-1 fish collected in 

 drop-trap samples (50 mm). Differences in the parameter 

 estimates for the von Bertalanffy growth equation were 

 observed for each sex. Males were larger than females 

 for all ages (Table 2). Although males exhibited a slower 

 growth rate (A") and larger maximum attainable size iL J 

 than females, the von Bertalanffy growth model param- 

 eters were not significantly different between sexes (95% 

 CI, Table 3). Male and female Mayan cichlids up to seven 

 years old were observed. 



The size of fish examined ranged from 21 to 210 mm 

 (median=127 mm, interquartile range=98 mm, « = 1046). 

 Males ranged from 69 to 210 mm (median=137 mm, inter- 

 quartile range=119 mm, ?;=400), and females ranged from 

 58 to 190 mm (median=132 mm, interquartile range=115 

 mm, 71=449) (Fig. 6). The length-frequency distribution 

 for males was significantly larger than that for females 

 (P<0.001). The overall ratio of males to females was 1:1.1. 



Age-frequency distributions of Mayan cichlids collect- 

 ed by hook-and-line gear suggest that these fish are 

 fully recruited to the fishery at age four (Fig. 7). The 

 majority of males (85.1'7r ) and feinales (81.5%) were 3-5 

 years old, and there was a significant difference (Mann- 

 Whitney rank sum ^test, P<0.001) in the age-frequency 

 distribution of males (median=3.67 years, interquartile 

 range=2.12) and females (median=4.78 years, interquar- 

 tile range=3.86). Total instantaneous mortality (Z), annu- 

 al survival (S), and annual mortality iA), based on the re- 

 gression of our catch-cui"v'e data, were estimated at 0.57, 

 0.56, and 0.44, respectively (/■-=0.91, n=3). Robson and 

 Chapman ( 1961) estimates were Z=0.91, S=0.40 (±0.035), 

 andA=0.60. 



Discussion 



Transverse otolith sections can be used to precisely age 

 Mayan cichlids from Florida waters. There was a high 

 congruence (98.7%) between the age estimations of each 

 reader Annuli corresponding to years 2-7 were clearly 



