Di Giacomo and Pener: Reproductive biology of Callorhynchus callorhynchus 



537 



o 



CD 



CD 

 CD 



CD 

 CL 





JAN FEB MAR MAY JUL AUG OCT NOV 



D 4 



3 



1 - 



— Left ovary 

 ( +s.d.) 



Right ovary 

  ( +s.d) 



B 



JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV 



Figure 7 



Females of the cockfish, Callorhynchus callorhynchus. (A) Per- 

 centage and average number (numbers above bars) of mature 

 ova by month; (B) mean number of mature ova per ovary by 

 month. 









s w^i 1 ; 1 



JAN FEB MAR APH MAY JUN JUL AUG SEP OCT NOV 



I ~ 1 EGG CASES 





FEMALE WITH SPERMATOPHORES 



tion. The absence of intermediate stages in 

 our materials can be explained by the fact 

 that sampling was conducted mostly between 

 90 and 130 meters, where adults prevail (Di 

 Giacomo, 1992). 



Mature females cannot be clearly defined. 

 Holden ( 1975 ) defined mature females of the 

 ray Raja clavata as those individuals that 

 had large, yellow oocytes in the ovaries. 

 Smith and Merriner (1986) distinguished 

 three stages of sexual maturity in females of 

 the cownose ray, Rhinoptera bonasus: imma- 

 ture, maturing, and mature. The mature 

 stage was characterized by the presence of 

 large, yellow oocytes greater than one cm in 

 diameter in the ovaries. The authors ac- 

 counted for the minimum length of gravid 

 females observed {R. bonasus is viviparous). 

 We could not identify which oocytes were 

 ready to be spawned in C. callorhynchus. 

 Although all yellow oocytes were viable, re- 

 sorption may lead to false conclusions regard- 

 ing spawning state. Therefore, the minimum 

 size fish that had egg cases in formation in 

 the nidamental gland was considered diag- 

 nostic, since at that stage resorption is no 

 longer possible. The smallest female with egg 

 cases in formation measured 50 cm (SL), and 

 the smallest female with mature oocytes was 

 48 cm SL. In females size at first maturity 

 was coincident with the minimum size offish 

 showing yolked oocytes and egg cases in 

 formation. 



McEachran (1970) found that in females 

 of the ray Raja garmani the oocytes in the 

 ovaries were half the size of those found in 

 the egg cases. In C. callorhynchus, the dif- 

 ference between the maximum size attained 

 by the oocytes in the ovaries and the eggs in 

 the case was about 25%. Assuming a similar 

 speed of yolk incorporation into the oocytes 

 for both species, we estimate that the females 

 of C. callorhynchus may have a higher 

 spawning rate than the ray, indicating that 

 maturing oocytes may attain ovulation size 

 faster. The maximum size of mature ova was 

 larger in C. callorhynchus than in other holo- 

 cephalan species such as Chimaera phan- 

 tasrna (Malagrino et al., 1981), C. monstrosa 



Figure 8 



Percentage of spermatophores and developing egg 

 cases in females of the cockfish, Callorhynchus 

 callorhynchus, by month. 



