750 



Fishery Bulletin 101(4) 



Female size at maturity 



180 



100 

 80 

 60 

 40 

 20 

 



100 

 80 

 60 

 40 

 20 

 



Koombana 

 Bay 



20 



60 



100 



140 



180 



Cockburn 

 Sound 



180 



60 100 140 180 



Carapace width (mm) 



60 100 140 180 



Carapace width (mm) 



Figure 3 



Logistic regressions and their 95% confidence limits fitted to percentage contribu- 

 tions of those adult females which, at each size, had undergone their pubertal molt in 

 each of the five bodies of water sampled in Western Australia. Arrows and measure- 

 ments denote CW^q's and the numbers in parentheses refer to the number of crabs 

 used to create the regressions. 



ent (P>0.05) and had steeper slopes than those determined 

 by using morphometric data (Fig. 4). The confidence limits 

 for the logistic curves constructed from gonadal data were 

 also usually tighter than those constructed from morpho- 

 metric data. 



The CWr,Q for male crabs with a loose abdominal flap 

 in Cockburn Sound, i.e. 72.1 mm, differed significantly 

 (/'<0.05) from that in Shark Bay, i.e. 76.2 mm (data not 

 shown). However, all of the male crabs in Cockburn Sound 

 with carapace widths of 70 to 75 mm and loosely attached 

 abdominal flaps contained gonads at stage I or II and were 

 thus immature. 



Trends exhibited by gonad weights and proportions of 

 ovigerous females 



The mean monthly gonad weight of mature female crabs 

 with a standard carapace width ( 104 mm), as determined 

 by ANCOVA (see "Material and methods" section), rose to 

 a sharp peak of about 5 g in October in Koombana Bay and 

 in September in Cockburn Sound (Fig. 5). In contrast, the 

 mean monthly gonad weights of mature female crabs in 

 the Leschenault and Peel-Harvey estuaries remained at 

 <1.5 g and did not tend to peak sharply at any time of the 

 year. The mean monthly gonad weights of mature female 



