256 
Fishery Bulletin 109(3) 
5 7 34 37 2 3 
Figure 5 
Percent frequencies of occurrence of mature females (ovaries at one of stages III to 
VIII) in sequential 50-mm total length classes and sequential age classes of estuary 
cobbler ( Cnidoglanis macrocephalus ) during the spawning period of this species. 
Logistic curves (solid lines) and their 95% confidence limits (dotted lines) were 
derived from logistic regression analyses of the relationship between total length 
and the probability that an individual fish was mature. Sample sizes for each length 
and age class are shown above each length and age class. 
Table 2 
Von Bertalanffy growth parameters and their 95% confidence limits (CL) derived from lengths at age of estuary cobbler ( Cnido- 
glanis macrocephalus) caught in Wilson Inlet, Western Australia, during 1987-89 and 2005-08. L oo =asymptotic length (mm); 
&= growth coefficient (per year); ( 0 = hypothetical age at which fish would have zero length (yr); r 2 = coefficient of determination; 
n= sample sizes; L mal =maximum lengths (mm); W max =maximum weights (g); and A max =maximum ages (yr). 
Von Bertalanffy parameters 
n 
^ max 
w 
max 
A 
max 
L m 
k 
*0 
r 2 
1987-89 
1301 
722 
2188 
13 
831 
0.24 
-0.09 
0.86 
Lower CL 
797 
0.22 
-0.16 
Upper CL 
864 
0.26 
-0.02 
2005-08 
758 
712 
2576 
8 
911 
0.21 
-0.22 
0.90 
Lower CL 
839 
0.18 
-0.30 
Upper CL 
982 
0.24 
-0.14 
at different lengths and ages, the maturation at a 
over each of the 120 consecutive months of the two peri- 
smaller size 
in the later period was accompanied by a 
ods did not differ significantly from zero (both P>0.05) 
reduction in the age at maturity (Fig. 6). 
Water temperatures 
The mean of the pairwise differences between the aver- 
age monthly air temperatures in corresponding months 
for either the minimum or maximum temperature. In 
other words, the air temperatures were not consistently 
greater in one period than the other. Because Wilson 
Inlet is shallow, the trends exhibited by these air tem- 
peratures will be reflected closely by the water tempera- 
tures of this estuary. 
