258 WHALES 



simplified if the oil for the sake of which they are killed could be obtained 

 direct from krill. In fact, \vhaling circles have given some thought to this 

 question and have even calculated how much it would cost to extract oil in 

 this way. It appeared that the project Avas wasteful both of resources and 

 of man-power, and the idea has been shelved, at least for the time being. 

 In future, atomic power may alter the situation, but the subject is still too 

 speculative to deal with at length. It must, however, be added that krill 

 oil as such is not fit for human consumption and would have to be con- 

 verted first, though it can, of course, be used for industrial purposes, just 

 like sperm oil. 



Another difficulty is that krill concentrations are very difficult to locate. 

 Attempts have repeatedly been made to use a 'fish lens', a kind of echo- 

 sounding apparatus, for tracing large swarms of krill, but so far with little 

 success. Whales seem to have the advantage over even our most up-to- 

 date scientific techniques, though there is hope that we may one day be 

 able to wrest their secret from them. 



In the Antarctic, krill is so profuse and so strongly concentrated that 

 the stomachs of whales are completely filled with krill and with very little 

 else. Even the odd fish, cuttlefish or penguin which they occasionally 

 swallow must have been a krill-feeder itself and have been sucked in 

 quite accidentally. Only off New Zealand, the Falkland Islands and 

 Patagonia do whales also feed on 'lobster krill', the larvae of crustaceans 

 known as Munida, while in the South Pacific, Rorquals augment their 

 diet of krill with two related crustaceans: Thysanoessa macrura and 

 Thysanoessa vidua. 



In Arctic waters, the diet is more varied. While Right Whales and Blue 

 Whales feed mainly on ki-ill like their southern relatives (though Arctic 

 krill is called Thysanoessa inermis and Aleganyctiphanes norvegica), they also 

 feed on Pheropods {Clio, Limacina). The Sei Whale with its finer baleen 

 normally restricts itself to a diet of somewhat smaller crustaceans [Calanus 

 finmarchicus) , though in the Northern Pacific it also feeds on cuttlefish. The 

 Californian Grey Whale, again, seems to be another exclusive krill eater, 

 feeding particularly on amphipods, though since it used to be caught 

 exclusively in Californian, Japanese and Korean waters where its stomach 

 is generally empty, we know little about its diet. The animal is supposed 

 to feed very close to the bottom of the sea. 



Northern Fin Whales, Humpback Whales and Little Piked Whales have 

 a far more varied diet. In the above regions, their stomachs were found to 

 contain not only krill and cuttlefish but also herring, mackerel, whiting 

 and other fish. In fact. Fin Whales eat so much herring in the North 

 Atlantic that the Norwegians call them 'Herring Whales' {Sillhval). 

 Because of this diet, other fish-eaters may fall accidental victims to them. 



