Griffiths: Life history and stock separation of silver kob, Argyrosomus modorus 
57 
mens below this length were mostly A. inodorus. Of 
the 11 size classes sampled in the southern Cape, 
eight contained more males and three contained more 
females (Table 3). However, the ratios of only three 
of these size classes (each with more males) were sig- 
nificantly different from the expected 1:1. Because 
more males were sampled within most size classes 
in the southern Cape, it would appear that there are 
more males than females in this region and that the 
lack of significance for several of the size classes could 
be due to limitations of the statistical test. The chi- 
square test is based on absolute differences (between 
observed and expected) and does not take into ac- 
count sample size, e.g. although a ratio of 1.2:1 
0 200 400 600 800 1000 1200 
Figure 8 
Percentage of mature female (gonad stage 3+) and male (gonad stage 3+ and drumming muscle stage 3) Argyrosomus 
inodorus by 50-mm total-length intervals, sampled during the spawning period in the southeastern Cape and in the south- 
ern Cape. The solid line describes the fitted logistical function. L 50 = median length at first maturity (mm total length); n = 
sample size. 
