62 



Fishery Bulletin 94|1). 1996 



Females There were representatives of all maturity 

 stages in the female sample (n=42), with considerable 

 variation in the size of stage-5 females (Fig. 3B). The 

 subsample of aged females (n-19) showed pronounced 

 variation in size and age (Fig. 5, A and B) due to the 

 greater size and age of the female sample (age range= 

 77-158 d). The majority of aged females were mature 

 (stage 5) and only eight immature ( stage- 1 and stage- 

 2) females were available for age analysis. Mature fe- 

 males ranged from 58 mm to 145 mm ML and from 94 

 to 158 d in age (Fig. 5, A and B). Although all immature 

 females were smaller than the smallest mature female, 

 some of the immature females were actually older than 

 some of the younger mature females. As with the males, 

 the small mature females were not only smaller but 

 younger than their larger mature counterparts. 



Discussion 



Genetic approaches to squid taxonomy and popula- 



tion studies are becoming increasingly important. 

 Electrophoresis has been a successful tool used in 

 the study of population variability within squid spe- 

 cies (Carvalho and Pitcher 1989; Garthwaite et al., 

 1989; Carvalho et al., 1992; Brierley et al., 1993, a 

 and bl. Furthermore, genetic techniques are becom- 

 ing increasingly important as an indispensable tool 

 in taxonomic studies (Brierley and Thorpe, 1994; 

 Yokawa, 1994). Recent work by Yeatman and Benzie 

 (1993, 1994) has demonstrated that electrophoresis 

 can distinguish cryptic species that are difficult to 

 identify morphologically. Continued use of genetic 

 analysis of squid populations is needed and will al- 

 most certainly reveal additional cryptic species (e.g. 

 Brierley et al., 1993, a and b). 



The short life-span and nonasymptotic growth dis- 

 played by Photololigo sp. 1 is similar to other tropi- 

 cal cephalopods in northern Australian waters (Jack- 

 son and Choat, 1992). This study suggests that there 

 might be sexual dimorphism in Photololigo sp. 1, with 

 females obtaining a larger size than males. Other 



