46 



DISCOVERY REPORTS 



actually thicker than when it is an adult 13-14 m. long, and is not only relatively fatter. 

 While the whale is growing from 8 to 10 m. in length the thickness of the blubber is in- 

 creasing very fast, but between the lengths of about 10 and 1 1 m. it decreases again as 

 rapidly. A similar state of the blubber is indicated by the curve for females, but is 

 shown less plainly because much fewer small female Humpbacks were measured than 

 males. 



In Figs. 46 and 47 the thickness of the blubber expressed as a percentage of the total 



c 



QJ 



IS- 



\^ 



I-3- 



O 

 b^l-l- 



in 

 If] 



QJ 



c 

 u 



h- 



L 



QJ 



_Q 



_a 



cn 



p -7. 



— — Adult, over 12 metres 



Immature, under 12 metres 

 O Adult 



sp O- 



Nov Dec Jan Feb Mar Apr Jun Jul Aug' 5ep 



Fig. 46. Humpback whale. Males. Seasonal variation in fatness. 



I- 



i_ 



QJ 

 J2 



Jun Jul Aug Sep' 



Nov 'Dec Jan Feb Mar Apr 



S Immature, under IS'Smetres 



^ Adult , pregnant 



Adult, over l2-5metres, resting" 



• O Adult. • Lactating- 



Fig. 47. Humpback whale. Female. Seasonal variation in fatness. 



length is plotted by months. Immature males under 12 m. long are plotted separately 

 from mature ones over 12 m. long in Fig. 46: immature females under 12-5 m. long, 

 mature but not pregnant females, and pregnant females are separated in Fig. 47. In 

 both charts the horizontal line represents the average blubber thickness of all whales. 



