296 



Fishery Bulletin 88(2). 1990 



Figure 1 1 



Increase of mean seminifenjus tubule diameter (■) and combined 

 testis mass (O) with age in male bottlenose dolphins captured off 

 southern Africa. 



Table 4 



Mean age. mass, and length of male bottlenose dolphins cap- 

 tured off southern Africa, with testes showing no mature 

 tubule development (stage 1), some ("^half) mature tubule 

 development (stage 2), and 75-100% of tubules mature (stage 

 3/4). 



Testis development stage 



1 



3/4 



Age 



Mass (kg) 

 Length (cm) 



4.68 

 90.8 

 201 



99 



14.3 

 1.51 

 228 



20.6 

 174 

 241 



Figure 12 



Increase in combined testis mass with mass and length in male 

 bottlenose dolphins captured off southern Africa. 



Male reproduction 



No consistent differences were found between mean 

 seminiferous tubule diameter of samples taken from 

 the outer, middle, and inner sections of testes. In gen- 

 eral, left and right testes were of similar mass (r = 0.95, 

 A'' = 46). Combined testis mass remained low (< 100 g) 

 up to approximately 10 years of age, approximately 

 140 kg body mass, and a length of 225 cm, but there- 

 after increased rapidly (Figs. 11. 12). Tubule diameter 

 growth and state of testes development (Mitchell and 

 Kozicki 1984) showed a similar pattern of growth with 

 age, mass, and length (Table 4, Fig. 11), although 

 development of tubules appeared to occur earlier than 

 did the increase in testis mass. The maximum mature 

 testis (stage 4) mass of any male was 1160 g and the 

 largest apparently immature testis (stage 1) was 1.30 g. 

 The smallest testis at stages 2, 3, and 4 were 140 g, 



Figure 13 



Influence of season (month) on combined testis mass (A) and mean 

 testis seminiferous tubule diameter (D) in male bottlenose dolphins 

 caiJtured off southern Africa. 



