209 



FOOD IN THE ANTARCTIC AND IN WARMER WATERS 



It is well known that whalebone whales feed during the Antarctic summer on the 

 shoals of the shrimp-like crustacean, Euphausia superba, collectively known as krill, 

 which inhabit mainly the surface waters of the Antarctic. This organism is of great 

 importance in the general economy of the sea in high southern latitudes, and its signi- 

 ficance as a supply of food for various animals besides whales has been illustrated by 

 Hart (1942, Text-fig. 16). Its life history and distribution are the subject of separate 

 reports already published or in preparation (see Bargmann, 1937 ; and Fraser, 1936). The 

 life history need not be considered here, and of its distribution it need only be said that 

 the work of the Discovery Committee's ships has clearly shown that it is confined to the 

 region south of the Antarctic convergence (see Deacon, 1937, p. 22), and that it is rarely 

 found even so far north as the convergence, its principal habitat being between the 

 3 C. isotherm and the coastal region of the Antarctic continent. The Committee has 

 accumulated very extensive data on its distribution. Mr J. W. S. Marr was preparing 

 a detailed report on the subject, but his work was interrupted by the outbreak of war, 

 and the full results are therefore not yet available. 



Here only some basic facts about the diet of whales will be discussed. To begin with, 

 there is no doubt about the specific identity of the krill. Several members of the 

 Discovery Committee's staff and various other biologists who are thoroughly familiar 

 with the species have examined the contents of thousands of whales' stomachs both at 

 South Georgia and in factory ships operating on various parts of the oceanic whaling 

 grounds, and these observers, not to speak of the personnel of the whaling factories, 

 could not fail to note any substantial variation of diet or any significant mixtures of 

 species in the food. This, however, is not to say that nothing but krill is ever to be found 

 in the stomachs of whales taken in Antarctic waters, and it is worth while here to give 

 some figures to demonstrate the heavy consumption of krill by the whales and the extent 

 to which other forms of food are found in their stomachs. 



The diet of whales at South Georgia, is dealt with by Mackintosh and Wheeler (1929, 

 pp. 361-4), who found that the vast majority of stomachs examined contained plenty 

 of food, and that this food consisted exclusively of Euphausia superba except for occa- 

 sional specimens of an Amphipod known to be common in the local plankton. The 

 Amphipod (Parathemisto gaudichaudi) constituted a wholly insignificant part of the diet. 

 Various observers have made notes on the stomach contents of whales taken on the 

 larger whaling grounds of the Antarctic. Perhaps the most detailed observations avail- 

 able to me are those of Major F. A. Spencer, who acted as Whaling Inspector in the 

 factory ship ' Southern Princess' during the seasons 1936-7 and 1937-8. He examined 

 the stomachs of several hundreds of whales, and noted the quantity of krill present, 

 whether large or small specimens predominated, instances of empty stomachs and in- 

 stances of any food other than krill. Table 5 is a rough analysis of these notes. The 

 figures are not exact, for no precise measurement could be made of the amount of krill 

 in a stomach, and it is not always certain whether absence of krill is to be attributed to 



