754 



Fishery Bulletin 101(4) 



between four and eight months old (Fig. 6). The prevalence 

 of mature crabs subsequently increased, with the result 

 that the vast majority of crabs in the following January, 

 i.e when they had just entered their second year of life, 

 were mature (Fig. 6). Thus, all crabs have typically become 

 mature when they are just over one year old. 



Fecundity 



In Cockburn Sound, the number of eggs recorded for 

 a single batch of eggs under the abdomen of a female, 

 ranged from 68,450 in a crab with a CW of 84 mm to 

 324,440 in a crab with a CW of 154 mm (Fig. 7). The rela- 

 tionship between batch fecundity (BF) and carapace 

 width (CW) is described by the following equation: lnfiF= 

 1.82081nCH'+3.2862. 



The estimated mean number of egg batches, produced by 

 female crabs in the different size classes over the spawn- 

 ing period, ranged from about one in crabs of 100-109 mm 

 CW to about three in crabs of 150-159 mm CW (Fig. 7). A 

 range of one to three batches per instar corresponds to that 

 recorded by Campbell ( 1984) for P. pelagicus in aquaria ex- 

 periments. The empirical relationship between the number 



of batches (NB) and carapace width (CW) is described by 

 A^Bj=l+2/{l+exp[-ln(19)(CW,-113.7)/13.8]|. 



A combination of the equations for the relationships 

 between batch fecundity and CW and the number of egg 

 batches and CW was then used to determine the relation- 

 ship shown between total fecundity (TF) and carapace 

 width (CW) and which is shown in Figure 7. 



Discussion 



Designation of maturity in male crabs 



Aquaria studies by Meagher (1971) demonstrated that 

 male crabs with gonads at stage 111, i.e. with spermato- 

 phores and seminal fluid in the medial vas deferentia, can 

 copulate successfully with females. Because this parallels 

 the situation recorded by Comeau and Conan (1992) for the 

 snow crab iChionoecetes opilio), we likewise regard such 

 gonads as mature. Our study also showed that, because 

 male P. pelagicus still possess immature gonads (stage II) 

 when their abdominal flap becomes loosely attached to the 

 cephalothorax, the latter change occurs at a prepubertal 



