DISTRIBUTION AND MIGRATION 337 



Blue and Fin Whales in the southern hemisphere, and we shall now 

 examine their migratory habits in the northern hemisphere. Now, all 

 three species are found over all the oceans of the world, though not to the 

 same extent. Thus we have seen that, in tropical and sub-tropical waters, 

 Humpbacks keep much closer to the coasts of the continents than Blue 

 and Fin Whales - no doubt one of the reasons why Humpbacks have 

 been caught in large number in Gaboon (Equatorial Africa) - and why a 

 number of them have been observed in Indonesian waters. 



The fact that Antarctic Blue and Fin Whales cross the equator is borne 

 out by strandings in Ceylon and on the Indian coast, by observations in 

 the Arabian Sea, and by some of the records made by Dutch officers who, 

 reported, inter alia, that on 23rd September, 1953, 30-50 Blue Whales 

 in groups of 3-4 were seen over an area of about ten square miles in the 

 Indian Ocean (at ii°i5' N. and 6o°2o' E.) and that the love-play of a 

 school of ten Fin Whales was observed on 9th June, 1955, at i8°i3' N. and 

 20°i2' W. (in the Atlantic). We are entided to assume that all these whales 

 were of Antarctic origin, for Arctic Rorquals are much farther north at 

 that time. It is even highly probable that South Atlantic Rorquals spend 

 the (southern) winter in the Caribbean and off the N. African coast. 



It is generally held that southern Humpback, Blue and Fin Whales 

 form a population distinct from their Northern counterparts. While both 

 groups can be found in warm waters every year, their chances of inter- 

 mingling are small, since at least the majority visit these waters at appointed 

 times of the year. During the winter, most of the northern whales are in 

 warm waters and most of the southern whales in the Antarctic, while in 

 summer (winter in the Southern hemisphere) a great number of the 

 northern whales are in the Arctic and the majority of the southern whales 

 move up towards the equator. However, occasional interchanges seem, 

 nevertheless, to occur and Zenkovich (1956), who believes that such inter- 

 changes are more common in the Pacific than in the Atlantic, bases this 

 opinion, inter alia, on the fact that a Rorqual caught off New Zealand was 

 found to be covered with northern whale lice (amphipods) while southern 

 parasites {Penella included) have been found on Blue and Fin Whales 

 caught off Japan, the Kuril Islands and Kamchatka. 



Despite the fact that the two groups are segregated, they show no 

 external or internal differences, so that there is no reason to refer to 

 separate strains. However, they do show certain behavioural differences. 

 We have seen that Antarctic Blue Whales keep mainly inside, and Antarctic 

 Fin Whales mainly outside, the zone of drifting ice, and while their counter- 

 parts in the N. Atlantic seem to behave similarly, those in the N. Pacific do 

 not. Japanese scientists have gone very thoroughly into this subject, and 

 in 1955 Omura reported that, though Blue Whales are never found 



