532 



Fishery Bulletin 92(3). 1994 



eter of the oocytes, number of individuals with egg 

 cases in formation or ready for extrusion, and presence 

 of spermatophores were recorded for females. Length 

 of the myxopterygia (males) was measured from the 

 insertion of the pelvic fin to the distal end (Fig. 2B). 



Figure 1 



(A) Location of the study area in the Argentinean 

 continental shelf; (B) San Matias Gulf. 



Indices of reproductive activity 



The annual reproductive cycle was assessed by us- 

 ing the monthly samples of the commercial catch 

 ( 1984-86). The gonadal index (GI), hepatic index (HI), 

 nidamental gland index (NGI, females only ) and green 

 gland index (GGI, males only) were calculated as 



GI: 



HI 



weight of the gonad 

 total weight 



x 100 



weight of the liver 

 total weight 



x 100 



NGI 



weight of the nidamental gland 

 total weight 



x 100 



_„ weight of the green gland 



GGI = E x 100 . 



total weight 



The duration of the mating season was estimated from 

 the presence of spermatophore masses in the female 

 cloaca and the annual cycle of the green gland index. 



Regression analysis was performed between the 

 indices of reproductive activity during the periods of 

 maximum activity and SL, and between the diam- 

 eter of mature oocytes and the number of immature 

 oocytes and SL. A Wilcoxon test was used to assess 

 the difference in the average number of mature ova 

 between right and left ovaries of all mature females. 



Sexual maturity 



The degree of development of the myxopterygia (male 



claspers ) relative to SL was used as 



an indicator of sexual maturity for 

 males (Holden and Raitt, 1975). The 

 size at first maturity in females was 

 determined by examining 1) the 

 percentage of mature females in 

 each 10-mm size class, 2) the maxi- 

 mum diameter of mature ovarian 

 eggs for each size class, and 3) the 

 smallest size class with egg cases 

 in formation. Females with yellow 

 ovarian eggs were considered mature. 



Figure 2 



irements for cockfish, Callorhynchus callorhynchus. (A) Standard 

 length; (B) myxopterygia length in male. 



Results 



Morphology of the 

 reproductive system 



The male reproductive system con- 

 sists of the following paired struc- 



