PERRIN ET AL.: GROWTH AND REPRODUCTION OF SPOTTED PORPOISE 



AVERAGE LENGTH AT BIRTH 



AVERAGE LENGTH AT BIRTH 



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LENGTH (cm) 



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LENGTH (cm) 



Figure 15. — Length-frequency distributions of postnatal male specimens ofStenella attenuata, 1968-73, by month. 



but in animals larger than about 200 cm, there is 

 little correlation with length. The largest testes 

 encountered weighed 2,400 g and were possessed 

 by a male 196 cm long. However, some males 

 more than 210 cm long had testes weighing less 

 than 300 g. Testes weight begins to increase 

 sharply at 50- to 55-kg body weight and is 

 strongly correlated with weight in larger ani- 

 mals. Males in the sample that weighed more 

 than 70 kg (eight animals) had testes weighing 

 more than a kilogram. The male with the third 

 heaviest testes (2,017 g — heaviest testes for 

 which body weight also available) weighed 80 kg; 



the heaviest male in the sample weighed 91 kg 

 and had testes weighing 1,348 g. A rapid increase 

 in testes weight (Figure 19) occurs at age 7 to 13 

 layers, with maximum size increasing until 12 to 

 16 layers. All animals with more than 14 layers 

 had testes weighing 500 g or more. Again, there 

 is wide variation in testes size relative to age. 

 Part of the variation is ascribable to the consider- 

 able error in the estimate of number of dentinal 

 layers (±2 layers for animals with more than 5 to 

 12 layers, more for older), but it must be con- 

 cluded that there is probably about a 5-layer 

 period during which the onset of puberty may 



245 



