FISHERY BULLETIN: VOL 77. NO 2 



zone between immaturity and maturity (Figure 

 11). 



By this definition, the smallest mature blue 

 shark (with spermatophores) in my sample was 

 153 cm and at 183 cm, 509c were mature. Judging 

 from the radii of male tooth cuts on females (dis- 

 cussed below) and the condition of the clasper, 183 

 cm is the average size at which male sexual matur- 

 ity is attained. Ninety-five percent of the males 

 >205 cm and lOC^ >235 cm were mature. 



These data agree well with Aasen's (1966) 

 length at sexual maturity for the male blue shark. 

 He cited 196.6 cm as the point of maturity as 

 determined by an analysis of clasper length and 

 my observations show 80% of the males contain 

 spermatophores at this size. Stevens' ( 1974) sam- 

 ple contained only one mature male blue shark. 

 He drew no conclusions regarding male maturity. 

 Stevens speculated that all of his blue sharks were 

 either immature or in a resting stage, except the 

 largest one which was in poor condition. By my 

 criteria, all of his sharks were immature except 

 this individual. Bigelow and Schroeder (1948) 

 suggested that both sexes mature in the range of 

 177-203 cm which agrees well with my finding of 

 183 cm. 



Afield test for the presence of spermatophores is 

 accomplished by making a cross-sectional cut 

 through the kidney at its thickest part. Four large 

 ( 10-15 mm) ducts are visible ventral to the kidney 

 at this level. Two of these are the thin-walled 

 ureters, usually filled with a clear fluid. The 

 thicker walled pair are the ampullae ductus defe- 

 rens containing several hundred cubic centime- 

 ters of spermatophores, 0.5-2.0 mm in diameter, 

 and their associated white flocculent supportive 

 tissue. The presence or absence of spermatophores 



140 160 laO 200 



BODY FORK LENGTH (cm) 



provides a positive answer to the question of sex- 

 ual maturity in an individual male blue shark. 



I observed no obvious seasonal fluctuations of 

 sperm production in the blue shark as have been 

 noted by Olsen (1954 ) and other authors for differ- 

 ent species of sharks. 



Female Anatomy 



Ovan and Epij;<inal Orfjan 



Only the right ovary of the blue shark i,s present 

 and functional. It lies at the anterior end of the 

 abdominal cavity adjacent to the liver and gall 

 bladder (Figure 12). The ovary is a large organ (25 

 cm X 6 cm) adnate to the forward lateral surface of 

 the right epigonal organ. It is roughly teardrop 

 shaped, corresponding to the expansion of the epi- 

 gonal organ as it reaches its forward terminus. 



ESOPHAGUS (CUT) 



OVIDUCT 



LOBE OF LIVER (CUT/ 



OSTIUM 



OVIDUCAL GLAND 



OVARY 



LEFT EPIGONAL ORGAN (CUT) 



ISTHMUS OF OVIDUCT 



RIGHT EPIGONAL ORGAN 



UTERUS (PAIRED) 

 KIDNEY 

 RECTAL GLAND 



PEL VIC FIN 



RECTUM 



VAGINA 



URINARY PAPILLA 

 ABDOMINAL PORES 

 CLOACA 



Figure ll. — Comparison of clasper length and spermatophore 

 presence with body length. Circles are clasper growth as percent 

 of largest clasper. Dots are percent of blue sharks with sper- 

 matophores. Dotted lines mdicate coordinates for 5(Xr maturity. 



5M 



Figure 12. — Female reproductive system in the blue shark, 

 general ventral view. 



452 



