McGovern et al.: Changes in the sex ratio and size at maturity of Mycteroperca microlepis 
803 
to reduce the potential for bias 
that might result from the selection 
of larger fishes after 18 April 1995, 
the Duncan multiple range test 
showed little difference in the mean 
size of gag collected each month 
(Table 8), and it was still apparent 
that transitional fish did not appear 
in the collections until immediately 
after the spawning season. 
Discussion 
Analysis of reproductive data in- 
dicates that the gag population 
along the southeast coast of the 
United States is stressed. The per- 
centage of males in the adult popu- 
lation has decreased from 19.6% 
(1976-82) to 5.5% (1994-95). How- 
ever, the percentage of males cur- 
rently in the population may ac- 
tually be less than 5.5%; more re- 
cent data were collected during the 
spawning season when male gag 
are most vulnerable to fishing gear 
(Coleman et al., 1996). In contrast, 
data were collected throughout the 
year during 1976-82 rather than 
primarily during the spawning 
season. Had the 1995 emergency 
rule been put into place at a time 
of the year when gag were not 
spawning, it is possible that fewer males would have 
been captured. 
The relative abundance of males and the length of 
the spawning period were greater off Florida than 
off other southeastern states. The highest percent- 
age of males ( 14.9%) during 1995 was noted off north- 
ern Florida. However, the majority of males were 
taken by one fisherman on 2 March 1995, 17 March 
1995, and 1 April 1995 indicating that this fisher- 
man may have been targeting a relatively unfished 
spawning aggregation. Spawning aggregations of gag 
(Coleman et al., 1996) and red hind, Epinephelus 
guttatus (Shapiro et al., 1993a), contained a higher 
percentage of males than nonaggregation groups. 
Commercial fishermen indicate that after the spawn- 
ing season (May and June), female gag move in 
groups to shallower water ( - 30 m ) and the larger males 
become solitary and remain at depths of 50 to 90 m. 
Probit analysis revealed that female gag may have 
been maturing at smaller sizes during 1994-95 than 
during 1976-82 which would further indicate that 
Total length (cm) 
Figure 2 
Comparison of the size frequency of immature gag, Mycteroperca microlepis , with 
the size frequencies of resting females and females with evidence of certain maturity. 
Table 8 
Total number sampled ( n ), mean total length ( mm TL; sexes 
combined), standard deviation (SD), number of males (M), 
number of females (F), and number of transitional speci- 
mens (T) by month for mature gag (>889 mm and <1050 
mm) captured during 1994 and 1995. Means with same 
letter are not significantly different (F>0.05). 
Month 
n 
if TL 
SD 
M 
F 
T 
Jan 
45 
932. 4 h 
41.5 
5 
38 
2 
Feb 
126 
935. 6 h 
42.5 
12 
114 
— 
Mar 
308 
948. 3“ 6 
46.4 
51 
257 
— 
Apr 
219 
939. 6" 6 
43.8 
27 
183 
9 
May 
92 
949.8" fe 
43.4 
24 
54 
14 
Jun 
25 
971.0 afe 
49.7 
7 
13 
5 
Jul 
41 
963. 1" 6 
46.7 
10 
30 
1 
Aug 
0 
— 
— 
— 
— 
— 
Sep 
3 
986.7" 
28.9 
2 
1 
— 
Oct 
2 
944.5 aft 
77.1 
— 
2 
— 
Nov 
10 
961.6" 6 
52.7 
1 
9 
— 
Dec 
11 
933.0'’ 
47.4 
2 
8 
1 
