THE HUMPBACK WHALE 43 



seasons. But even this difference cannot be taken as separating physiological races, for 

 Hinton (1925) points out the possibility of southern whales sometimes joining the 

 northern schools. As is shown in a later section of this report, breeding, though mainly 

 restricted to a season of about three months, extends to a lesser degree throughout the 

 year. Consequently a southern female, impregnated at the usual time, joining a northern 

 school would not appear as a striking anomaly if examined, although she would be in a 

 widely different stage of pregnancy from the majority of northern whales. In fact, if 

 she joined in the migration of the northern schools she would by that become one of the 

 "northern race", so even the physiological difference is merely an outcome of locality. 



FOOD 



Table XIII shows the stomach contents of fifty Humpback whales from South 

 Georgia and South Africa. It shows quite clearly that in general the Humpbacks at 

 South Georgia are feeding, whilst those on the coasts of South Africa are not. It must 

 be remembered that Humpbacks are now only taken at South Georgia when there is a 

 scarcity of other species of whale, a scarcity which is frequently correlated with a scarcity 

 of krill, and consequently it is not surprising that out of thirty-three stomachs examined 

 six were empty and thirteen contained very little food. The krill found in the stomachs 

 of Humpback whales at South Georgia consists entirely of Enphaiisia superba in various 

 stages of growth. Four typical analyses of stomach contents are given in Table XIV. 

 On the South African coasts, however, the Humpback whale stomachs were found to be 

 entirely empty of krill, not even containing the small species of euphausians found in 

 the stomachs of Fin and Blue whales. Two stomachs, on the other hand, contained fish 

 remains. One, that of a male no. 793, 9-92 m. in length, taken 25. vi. 26, was crammed 

 with fishes noted as " } Clupeoids", while the other, that of a female no. iioi, 11-27 ™- 

 in length, taken 20. ix. 26, was filled with a pasty mass of fish scales and bones. Olsen 

 (1914-15) gives a photograph taken at Saldanha Bay of a Humpback whale stomach 

 filled with fishes about the size of herrings. The food of the southern Humpback whale 

 appears thus to be similar to that of the northern race, which, according to Millais(i9o6), 

 consumes quantities of capelan when krill is not available. 



It has been shown elsewhere (Matthews, 1932) that off the coast of Patagonia the 

 Humpback feeds on the shoals of the pelagic Grimothea post-larva of Munida gregaria, 

 in company with Sei whales ; and that off the Pacific coast of Mexico an allied crustacean, 

 Plenroncodes planipes, which also swarms near the surface of the sea, is eaten. 



BLUBBER 

 Data relating to the blubber are recorded from fifty-seven Humpbacks and are sum- 

 marized graphically in Figs. 44-47. Figs. 44 and 45 show the thickness of blubber 

 plotted against the total length of whale. South Georgian and South African whales 

 being plotted separately. These graphs show that above a total length of about 10 m. 

 the thickness of the blubber varies with the total length in both localities. South African 

 females in the present series are thinner than those from South Georgia, but the males 



