PERRIN ET AL.: GROWTH AND REPRODUCTION OF SPOTTED PORPOISE 



1 2 



•1971 I 1972-^ 



MONTH 



Figure 6. — Linear regression analysis of modal lengths of fetal 

 and neonatal specimens of Stenella attenuata (from Figure 4). 

 Open circles are modes not included in the analysis. Modal 

 lengths defined with computer program NORMSEP (see 

 Materials and Methods). 



05 



CJ> 



0.4 



0.3 



0.2 



0.0 



\ 



\ 



\ 



\ 



\ 





100 200 300 400 500 



GESTATION PERIOD (days)-tg 



Figure 7. — Ratio toltg interpolated between empirical esti- 

 mates of Huggett and Widdas (1951) — ". . .for gestation times up 

 to 50 days ^o ~ 0.4 x (gestation time), from 50-100 days 

 <o-0.3 X (gestation time), from 100-400 days <o- 0.2 x (gestation 

 time), over 400 days t^— 0.1 x (gestation time)." 



L = 82.5 + 5.42 t, 



where L = length in centimeters 



t = postnatal age in months. 



Analysis Based on Analogy with Other Cetaceans 



Fetal growth in length of cetaceans, except for 



40 



30 



20 



10 







50 



40 



30 



20 



10 



FEBUARY 1973 



20 



10 



80 96 112 128 144 160 176 192 208 



LENGTH (cm) 



Figure 8. — Length frequencies of fetuses and postnatal speci- 

 mens of Stenella attenuata between 64 and 204 cm long, of 

 both sexes, by month. 



an initial slow phase {t^), is nearly linear. Post- 

 natal growth during at least a period equivalent in 

 length to the gestation period is also nearly linear, 

 but at a lower rate. The difference between the 



237 



