662 



Fishery Bulletin 89(4). 1991 



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o AUGUST- SEPTEMBER 



 JUNE-JULY 



• APRIL- MAY 



125 130 135 140 145 



TOTAL LENGTH(cm) 



150 



Figure 10 



Relationship between total body length 

 and uterine fecundity in the school shark 

 Galeorhinus galeus, from Rio Grande do 

 Sul, Brazil. 



Gestation 



Outgrowths of the uterine wall divided the uterus 

 into separate gestation chambers for each em- 

 bryo. The quantity of liquid in the chambers of 

 the two uteri increased from about 200 g in April 

 to 500-900 g in July, constituting respectively 8.3 

 and 28.0% of the weight of the full uteri in those 

 months. Uteri were swollen and turgid due to the 

 increasing mass of the litter and liquid, and in July 

 attained weights between 1230 and 5520g. 



Embryos situated near the cloaca were about 

 2-4 cm larger than those situated near the 

 nidamentary gland. In August and September, 

 but not in April, mean total length per litter in- 

 creased linearly with total length of the mother 

 (Table 1, Fig. 11). This indicates that embryos 

 grow faster in the larger females. 



The weight of 38 large follicles of ovulating 

 females varied from 42 to 56 g. The weight of 59 

 newly ovulated eggs varied between 40 and lOOg 

 with a mean of 59. 4g, which is the magnitude of 

 the yolk reserve in the egg. From April to 

 September, mean total length and yolkless weight 

 of the embryos increased from 13.3 to 28.0cm and 

 from 10.0 to 65.0 g, while the weight of the full 

 yolksac decreased from 45 to 17g. There was no 

 yolksac in a litter of 28 embryos in November. 

 These embryos averaged 30.3cm TL and 92. 9g 

 total weight. The sex ratio of embryos did not dif- 

 fer significantly from unity: 599 were males and 

 625 were females. 



Cycle of the liver 



In sexually immature sharks, the hepatosomatic 

 index (HSI) did not change with body size but 

 varied about the mean of 7.9 throughout the 

 range of total lengths. The HSI of males increased 

 at sexual maturity to a mean of 11.4 (Fig. 12). 



Figure 1 1 



Relationship between total body length 

 of the mother and mean length in litter 

 of the school shark Galeorhinus galeus, 

 from Rio Grande do Sul, Brazil. 



