536 



Fishery Bulletin 92(3), 1994 



ferent ducts and the first part of the deferent ducts, 

 and 3) accumulation in the green gland during the 

 formation of spermatophores. Activity of the female 

 gonads and nidamental glands is synchronous be- 

 cause as the oocytes mature they are ovulated and 

 immediately encapsulated in the nidamental glands. 



Unlike most elasmobranch species in which one 

 ovary is functional and the other is vestigial 

 (Mellinger, 1972; Menni et al., 1979; Teshima, 1981; 

 Natanson and Cailliet, 1986; Smith and Merriner, 

 1986), the left and right ovaries of C. callorhynchus 

 are both functional. However, the average number 

 of ova produced in each ovary is different. As in H. 

 colliei, the egg cases of C. callorhynchus are produced 

 simultaneously by both of the nidamental glands 

 (Dean, 1906). 



Changes taking place in the development of the 

 gonad and the green gland of males suggest that re- 

 productive activity is continuous, with a period of 

 rest or recovery around March. Relatively high fe- 

 male index values in February can be considered a 

 continuation of the main period of reproductive ac- 



tivity. The sample of females analyzed in January 

 was probably not representative because of their scar- 

 city in commercial landings. Resting or recovery may 

 last one or two months in C. callorhynchus, while 

 males and females of C. monstrosa and C. phantasma 

 have a resting period of six months ( Vu Tan Tue, 1972; 

 Malagrino et al., 1981). 



Sexual maturity 



A threshold value in the GI has been utilized to sepa- 

 rate immature and mature females in some teleost 

 species in which oocytic resorption has not been ob- 

 served. In C. callorhynchus such a GI threshold cri- 

 terion must be coupled with macroscopic observation 

 of the ova in the ovary; in the case of low GI values, 

 presence or absence of atrophied ova is indicative of 

 resting or immature conditions, respectively. 



Development of the myxopterygia is diagnostic of 

 male maturity in C. callorhynchus, allowing the iden- 

 tification of the length at first maturity. Transition 

 between stages can be related to an offshore migra- 



10 



8 



7 

 6 

 5 

 A 

 3 



: 





JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV 



JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV 



EB MAR APR MAr JUN JUL AUG SEP OCT NOV 



Figure 6 



Indices of reproductive activity of females of the cockfish, Callorhynchus callorhynchus. (A) Gonadal index (GI); (B) 

 nidamental gland index (NGI); (C) hepatic index (HI). 



