FISHERY BULLETIN: VOL. 81. NO. 1 



with spherical seminiferous ampullae, much the 

 same as are found in spiny dogfish (Simpson and 

 Wardle 1967) and blue shark (Pratt 1979). Histo- 

 logical sections of mature testes demonstrate 

 that these ampullae contain spermatozoa in vari- 

 ous stages of development (Fig. 6). Viewed in 

 cross section, the heads of the mature spermato- 

 zoa are arranged in discrete groups around the 

 periphery of the spherical ampullae. 



The spermatozoa leave the testis by way of the 

 efferent ductules and enter the epididymis. The 

 epididymis is a paired organ located above the 

 testis against the dorsal wall of the abdominal 

 cavity. The sharpnose shark's epididymis is 

 about 15 cm long, 1.0 cm wide, and 0.5 cm thick. 

 Histological sections of an epididymis from a re- 

 productively active sharpnose shark reveal great 

 numbers of spermatozoa present in the tubules 

 of the organ (Fig. 7). 



Maturation 



Males 



Maturity in animals can generally be deter- 

 mined by comparing external secondary sex 



characters in adults with the same characters in 

 smaller individuals. Using two indicators of sex- 

 ual maturity (i.e., clasper growth and siphon-sac 

 development), it was determined that matura- 

 tion of the male Atlantic sharpnose shark begins 

 at about 60 to 65 cm TL and is complete at about 

 80 cm. 



At <65 cm TL the clasper length represents 

 about 2.5% of the adult total length. Regression 

 analysis shows that the claspers undergo a period 

 of rapid growth with a major inflection in the 

 line occurring at 65 to 70 cm TL (Fig. 8). The 

 claspers quickly elongate, growing 3 cm within a 

 short period of time to represent 7 to 8% of the 

 total length. The smallest mature males exam- 

 ined were about 80 cm long and their claspers 

 represented about 7.8% of total length. There 

 were many individuals examined between 75 

 and 80 cm TL that possessed elongated claspers, 

 but incomplete calcification of the claspers indi- 

 cated that the specimens were not mature. 



The clasper grows faster than the total length 

 at the onset of maturation and for a short period 

 into adult life. Regression analysis indicates that 

 from about 85 to 95 cm TL the relationship is un- 

 changing, but after 95 cm there is a period of 



Figure 6.— Histological section of a testis from a mature Atlantic sharpnose shark (X440). The cross sections 

 show that the heads of the mature spermatozoa are arranged in discrete groups around the periphery of the 

 spherical seminiferous ampullae. 



66 



