348 WHALES 



travels from the Bering Sea down to Southern Cahfornia (about 20° N.) on 

 the American side, and from the Sea of Okhotsk to Korea (35° N.) in the 

 Western Pacific. Gilmore (i960) has shown that the American stock 

 travels southward far from the coast, but that they are close to the coast 

 ^vhen they go northward. In so doing they swim most of the time with 

 the cinrent. It seems likely that, not so long ago, the Grey Whale was far 

 more widespread and that it occurred in the N. Atlantic as well. From 

 recent finds of bones of the Californian Grey Whale in the Wieringermeer 

 polder and other parts of the former Zuider Zee first described by A. B. 

 van Deinse and G. C. A. Junge in 1937, together with other fossil material, 

 we know that the Grey Whale must have frequented the N. Atlantic 

 between 4000 and 500 B.C., and probably till fairly recently, since the 

 'Scrag Whale' described by Dudley off New England in 1825 may well 

 have been a Californian Grey Whale. 



Exclusively North Atlantic species are the White-sided Dolphin 

 Lagenorhynchns acutus, the White-beaked Dolphin Lagenorhynchus albirostris, 

 two Beaked Whales: Alesoplodon bidens and Mesoplodon europaeus (see Fig. 

 191), together with the Common Porpoise, with which we must conclude 

 our discussion of the distribution and migration of Cetaceans.^ Despite 

 the fact that porpoises are so common, we know little about their migra- 

 tion except that they travel as far north as the Davis Strait, Greenland, 

 Spitsbeigen and the White Sea. Off the American coast, porpoises have 

 been observed as far south as 38° N., and specimens have also been washed 

 ashore near Dakar. Porpoises are true coast-lovers, and are found in the 

 Baltic, the Mediterranean and the Black Sea and quite a long way up the 

 larger rivers. Thus porpoises have been caught in the Rhine (near 

 Cologne), the Nethe (near Lierre), the Seine, and the Meuse (near 

 Venlo). It is also known that the North Sea population increases in the 

 spring to reach a maximum in July and August when the young are born, 

 and that, from November to February, porpoises desert the Baltic Sea. 

 Unfortunately, we have no idea what connexion there is between these 

 movements themselves, or between them and a possible migration to the 

 south. 



^ It is not yet clear whether the rare N. Pacific porpoise Phocaena vomerhia belongs to 

 the same species as the Common Porpoise. 



