Zhao and McGovern. Variation in sexual maturity and sex ratio of Rhomboplites aurorubens 
843 
latitudes with other factors (length, period, and gear) 
remaining consistent. Six of the 14 tested cases indi- 
cated that sex ratio was dependent on latitude (Table 
4). Even after allowance for multiple-testing ( ct'=0.05/ 
14=0.0036), there were still two cases indicating sig- 
nificant difference (1979-81, trawl, 150-199 TL and 
1988-90, traps, 200-249 TL). Because the latitudi- 
nal distribution of samples was not similar among 
periods for any gear type (Table 2), we used only data 
from the latitude of 32°N in subsequent analyses. 
There were no significant differences in percent- 
age of females caught by traps among length classes 
200-249, 250-299, and 300-349 mm during 1982- 
84, 1988-90, or 1991-93 (Table 5). During 1979-81, 
the hypothesis of independence between sex ratio and 
length was rejected for fish caught by hook-and-line 
within the length range of 150-449 mm. However, it 
was not rejected within 200-299 mm (Table 5). Thus, 
the common TL range of vermilion snapper caught 
by hook-and-line was 200-299 mm, within which the 
sex ratio was independent of length during 1979- 
93. There were no significant differences in percent- 
ages of females caught by trawl within 150-249 mm 
during 1979-81 and 1985-87 (Table 5). After allow- 
ance for multiple-testing ( a'=0. 05/12=0. 004), none of 
the 12 cases showed significant difference. 
We compared the percentage of females among 
periods by pooling data for each gear type within the 
common TL range and periods when the sex ratio 
was independent of length. There were no signifi- 
Table 4 
Comparison of percentages of females among latitudes with the same length ranges (TL=200-249 mm and TL=250-299 mm), 
period, and gear type. All data were pooled from various water depth classes. % = female percent, n - the total number of male 
and female fish. The null hypothesis ( H 0 ) = sex ratio is independent of latitude. Blanks indicate no or few samples available for 
comparison. 
Traps Hook-and-line Trawl 
Latitude TL=200-249 TL=250-299 TL=200-249 TL=250-299 TL= 150-199 TL=200-249 
Period (°N) % n % n % n % n % n % n 
1979-81 31 
32 
33 
chi-square 
P 
df 
Reject H 0 
1985-87 31 82.6 
32 84.6 
chi-square 0.234 
P 0.629 
df 1 
Reject H 0 No 
1988-90 31 63.9 
32 73.7 
33 91.8 
chi-square 11.96 
P 0.003 
df 2 
Reject H 0 Yes 
1991-93 31 80.0 
32 68.8 
33 77.7 
chi-square 9.509 
P 0.009 
df 2 
Reject H 0 Yes 
57.1 
14 
87.5 
73.6 
106 
67.6 
87.5 
16 
50.0 
Fisher’s 1 2 
Fisher’s 2 
0.178 
0.352 
No 
No 
115 
50.0 
20 
72.7 
11 
93.3 
266 
74.4 
168 
65.6 
96 
67.2 
5.258 
Fisher’s 2 
Fisher’s 2 
0.022 
0.747 
0.039 
1 
Yes 
No 
Yes 
36 
100.0 
4’ 
392 
70.5 
291 
61 
76.7 
30 
0.511 
0.475 
1 
No 
235 
57.1 
7 
276 
76.8 
207 
206 
60.0 
20 
3.925 
0.141 
2 
No 
8 
36.5 
115 
57.1 
14 
105 
60.2 
103 
57.4 
101 
4 
12.205 
0 
<0.001 
0.984 
1 
1 
Yes 
No 
15 
39.4 
221 
52.3 
44 
131 
58.3 
36 
61.7 
154 
4.571 
1.260 
0.033 
0.262 
1 
1 
Yes 
No 
1 The row was discarded from the contingency table because of its excessively low expected frequency. 
2 When conditions for a chi-square test were not met, Fisher’s exact test was used. 
