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Fishery Bulletin 98(2) 



Fiyure 1 



Isurus oxyrinchus embryos and egg cases. (Al 3-cm-TL embryos with external gills, large yolk sac, and still within the egg cases 

 from right uterus of pregnant female (no. 3 in Tables 1 and 2). Embryo in the center was removed from egg case. (B) Right uterus 

 containing 42 nutritive egg cases from female with embryos shown in A. Scale bar, 10 cm (C) Embryo from a litter of 15 with 

 mean TL=52.0 cm and mean mass=2.000 kg with large yolk stomach of estimated dimensions 19 v 12 cm (no. 16 in Table 1(. 

 (Di Embryo from a litter of 9 (mean TL=59.9 cm, mean mass=2.426 kg, mean yolk mass=29.1%, mean HSI=3.7'7f ) dissected to show 

 yolk stomach, spiral valve, and right liver lobe. Upper jaw cartilage is visible and emerging adultlike teeth are present in both jaws 

 (no. 20 m Table 1). Scale bar, 30 cm. 



in -17) and overlapped considerably with that in 

 mature sharks which had a range of 1-8 mm (n-26). 

 The blastodisc ova appeared to be 6-8 mm in dia- 

 meter, given the MOD of 8 mm and the estimated 

 spherical diameter of 7 mm of the yolk sac of a 3-cm 

 embryo (Fig. 2B). Nutritive eggs appeared to have 

 a slightly smaller diameter at 4—6 mm. This dia- 

 meter was based on a MOD of 6 mm for the female 

 in early pregnancy (Fig. 2B) and on the 4-mm ova 

 found in the uteri of two fertilized South African 

 females (Table 2). A spent ovary in a female with 

 large embryos also contained 6-mm ova (Fig. 2B). 



The oviducal gland remained undeveloped until 

 the onset of maturity and then increased rapidly in 



diameter in females of 2.7-3.0 m, as they matured 

 (Fig. 20, western North Atlantic specimens only). 

 The range in immature fish was from 0.1 to 1.1 cm 

 in -32). There was considerable overlap in the dia- 

 meter of the adolescent oviducal gland, ranging from 

 2.5 to 4.7 cm (n = ll) and in the diameter of mature 

 females, ranging from 2.3 to 5.1 cm (« = 19). The ovi- 

 ducal gland diameter of two pregnant females, one 

 with early-term, the other with near-term embryos, 

 were similar (4.9 and 4.2 mm, respectively) to that of 

 nonpregnant mature females. 



Uterus width provided the best indication of matu- 

 rity. There was little overlap between immature fe- 

 males in the range of 0.3-6.5 cm (mean 1.6, SE=0.2, 



