840 
Fishery Bulletin 95(4), 1997 
of independence between sex ratio and depth was 
not rejected, the data from all depth classes were 
pooled to compare further the percentage of females 
among latitudes, other factors (length, period, and 
gear) being consistent. If the hypothesis was rejected, 
data from a certain depth class were chosen for fur- 
ther comparison. In a similar fashion, we compared 
the percentage of females among length classes, pe- 
riods, and gear types. 
The statistical methods available in SAS were used 
to analyze data of maturity and sex ratio (SAS Insti- 
tute, 1990). Rejection of the null hypothesis was 
based on a significance level of 0.05, unless other- 
wise noted. 
ResuSts 
Maturity schedules 
Males and females collected in 1982-84 and 1985- 
87 became sexually mature at a smaller size than 
individuals collected in 1979-81 (Fig. 1). For in- 
stance, 31% of male vermilion snapper collected in 
1979-81 were mature at 140 mm. However, 100% of 
males taken at the same size during 1982-90 were 
mature. All fish taken in May and June of 1991-93 
were larger than 180 mm and mature, and therefore 
were not included in our analysis. There was a sig- 
nificant temporal increase in the percentage of ma- 
ture males among 1979-81, 1982-84, and 1985-87 
at 120 mm (Fisher’s exact test: two-tailed P<0.01), 
and at 140 mm (two-tailed P<0.005). The percent- 
age of mature females also showed a significant in- 
crease with time for 140-mm individuals collected 
between 1979-81 and 1985-87 (two-tailed P<0.005). 
The observed differences in the percentage of ma- 
ture females at 160 mm collected during 1979-81, 
1985-87, and 1988-90 were not statistically signifi- 
cant (Fig. 1). Males larger than 140 mm and females 
larger than 160 mm were not tested because all fish 
were mature. 
The likelihood ratio tests indicated that the probit 
model could be used to describe the maturity at 
length during 1979-81 for both males (likelihood 
ratio x 2 =2.721, P>0.10) and females (likelihood ratio 
% 2 =1.407, P>0.10), and for females during 1985-87 
(likelihood ratio ^ 2 =4.647, P>0.10). The median TL 
at maturity of males was 145 mm (95% limits: 135- 
203 mm) during 1979-81. The TL 50 of females was 
160 mm (95% limits: 155-164 mm) in 1979-81 and 
151 mm (95% limits: 143-156 mm) in 1985-87. 
There was a significant increase in the percentage 
of mature age-1 males with time between 1979-81, 
1982-84, and 1985-87 (Fisher’s exact test: two-tailed 
P=0.013) (Table 1). The percentage of mature age-1 
females increased (G=5.318,P=0.021) between 1979- 
81 and 1985-87. More than twice as many age-1 fe- 
males were mature in 1985-87 (48.6%) as in 1979- 
81 (23.1%). The median age at sexual maturity could 
not be calculated because of the abrupt transition 
from immature to mature. 
Males matured at a smaller size and younger age 
than females (Fig. 1; Table 1). During 1979-81, TL 50 
for males ( 145 mm) was smaller than that for females 
(TL 50 =160 mm). Although TL 50 for males in 1985-87 
could not be calculated, it was observed that the TL 50 
of males declined with time faster than that of fe- 
Tab!e 1 
Percentages of sexually mature vermilion snapper caught in May and June of 1979-93. Numbers of fish in each category are 
given in parentheses. Blanks indicate no data available for that category. There were significant (P<0.05) differences in percent 
mature of age-1 fish among periods for each sex. 
Period 
Age 1 
Age 2 
Age 3 
Ages 4+ 
Males 
1979-81 
63.6 (11) 
100.0(15) 
100.0(12) 
100.0 (13) 
1982-84 
85.7 (7) 
100.0 (28) 
1985-87 
100.0 (19) 
100.0 (12) 
100.0(10) 
100.0(55) 
1988-90 
100.0 (2) 
100.0 (4) 
100.0 (4) 
100.0 (47) 
1991-93 
100.0(1) 
100.0 (32) 
Females 
1979-81 
23.1 (39) 
91.3 (23) 
100.0 (9) 
100.0(9) 
1982-84 
100.0(4) 
100.0 (6) 
100.0 (67) 
1985-87 
48.6 (35) 
95.8 (24) 
100.0 (18) 
100.0(135) 
1988-90 
100.0 (2) 
100.0 (8) 
100.0 (10) 
100.0(104) 
1991-93 
100.0 (3) 
100.0 (86) 
