THE HUMPBACK WHALE 



8i 



immature, and the second ones mature, whales. It is therefore evident that the propor- 

 tion of immature whales is small on the southern migration, but that off the coasts of 

 South Africa immature whales form a much greater part of the population. This is 

 borne out by the statement of Olsen (1914-15) that between the periods of migration the 

 whales caught at Durban are nearly all sexually immature and one to two years old; and 

 that the whales arriving off the south-west coast of Africa on the northward migration 

 are often accompanied by young of the previous season about 30 ft. long, which leave 

 their parents and form schools of their own, roaming about in the waters of that region 

 while the adult whales continue their migration to the north. This statement is 

 supported by the data collected by the Discovery staff in South Africa. The lengths 

 of all the Humpbacks examined there are shown in Table XXIV. The figures from 



Table XXIV. Humpback whale. Lengths of whales examined 



in South Africa 



Durban for 1930 are particularly interesting: in June the one whale examined was 

 sexually mature, in July none of the six seen were, but in August sexually mature whales 

 appear again. 



Townsend (1935) gives a chart in which are plotted the position and date of capture of 

 2883 Humpback whales taken by American whalers during the nineteenth century and 

 first decade of the twentieth. This shows that Humpbacks were taken in the northern 

 hemisphere between latitudes 40" N and 10^ N, mostly in October to March inclusive, 

 and in the southern hemisphere between latitudes 40" S to 10° N, mostly in June to 

 September inclusive. The incidence of this whaling agrees closely with what would be 

 expected from a consideration of the conclusions drawn above as to the times and course 

 of the annual migrations of the Humpback. From an examination of this chart it appears 

 that the southern Humpback regularly passes north of the equator for a distance of 

 several degrees of latitude during its migration. It has been suggested that this species, 

 sometimes at least, passes through the tropics from the temperate regions of one hemi- 

 sphere to those of the other, and this appears to be very possible. Hinton (1925) says 

 that southern Humpbacks that have passed well over the equator may meet herds of 



