Di Giacomo and Perier: Reproductive biology of Callorhynchus callorhynchus 



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tures: testes, epididymis (efferent ducts), and defer- 

 ent ducts (Leigh-Sharpe, 1922). In sexually mature 

 individuals, the deferent ducts are differentiated into 

 two fusiform structures called green glands (Fig. 3A). 

 These structures agglutinate the spermatozoa into 

 spermatophores and secrete a gelatinous, green fluid. 

 The reproductive system of the female is composed 

 of the following paired structures: ovaries, oviducts, 

 nidamental or shell glands, uteri, and vaginal open- 

 ings that end in a cloaca (Fig. 3B). 



Holocephalans are sexually dimorphic. Male sec- 

 ondary sexual structures (frontal tenaculum, and 

 prepelvic and pelvic claspers) are utilized during 

 mating (Fig. 4); the male apparently inserts the mass 

 of spermatophores into the seminal receptacle of the 

 female cloaca. Upon macroscopic examination (Oc- 

 tober), a mass of spermatophores was found at the 

 female genital opening. Spermatozoa are liberated 

 progressively by an unknown mechanism, before fer- 

 tilization. 



Females extrude fertilized eggs enclosed within a 

 leathery case (Dean, 1906) that acts as protection 

 for the embryo during development. At hatching the 

 fry resembles the adult. 



Indices of reproductive activity 



The GI of males reached a maximum in March (3.0) 

 and was low from July to October (range seen in Fig. 

 5A). The highest mean values of the GGI were found 

 between July and October (Fig. 5B), although the 

 index was also high during January and February. 

 In females, the GI reached its highest values from 

 July to October, indicating low reproductive activity 

 during the rest of the year (Fig. 6A). The NGI (fe- 

 males) has two periods of activity: July to November 

 (highest) and January to June (lowest) (Fig. 6B). The 

 HI for both males and females (Fig. 5C, 6C) did not 

 show significant annual fluctuations; maximum val- 

 ues occurred simultaneously with peaks in the other 

 reproductive indices. 



Mature and immature females could be differenti- 

 ated based on GI values (range: 0.13 to 4.55); a GI 

 value larger than 1.0 was characteristic of mature 

 females. The presence in March of some females 

 smaller than 50 cm SL with a GI higher than 1.0 

 and ovaries with translucent oocytes was suggestive 

 of oocyte resorption. Oocyte diameter varied between 

 10 and 35 mm. 



testes 



epididymis 



ovaries 



genital 

 opening 



Figure 3 



Reproductive organs of the cockfish, Callorhynchus callorhynchus. (A) Males; 

 (B) females. 



