,46 DISCOVERY REPORTS 



The fantastic numbers in which the krill are consumed by whales alone may be compared with the 

 impact of the northern herring upon Temora longicornis. In January 1872, Howell (1921) records, 

 Kiel harbour was crammed with herrings for three weeks, ' and each herring was crammed with a 

 compact pink bolus consisting of about 60,000 Temorae'. 



Using Guldberg's figures, which suggest on average full stomach content of about i ton,^ the annual 

 toll of the krill exacted by the southern rorquals would work out at about 19 million tons, still an 

 enormous figure. A ton in fact might not be an improbable estimate for an average full stomach content, 

 Nishiwaki (1950) having given figures showing that in 61 whales, 32 blue and 29 fin, ranging fairly 

 from 61 to 89 ft. in total length, the average weight of the stomach when empty is over | ton, the 

 lightest, in a 61 -ft. fin, weighing 2 cwt., the heaviest, in an 83 -ft. blue, over \ a ton. In the much 

 smaller northern sei whale Fujino (1955) finds the average weight of the empty stomach in twenty 

 40-45 ft. specimens to be over 2 cwt., a similar figure being found by Omura (1957, 1958) for the 

 empty stomach of a 38-ft. North Pacific right. 



It is interesting to compare these recent Japanese figures with the earlier findings of Captain T. 

 Sorlle, who, while manager of the Vestfold Whaling Company, South Georgia, was the first to dis- 

 member baleen whales and weigh the viscera piecemeal. He obtained the following results. Stomach 

 of a blue whale, 20-30 m. (66 ft.) long, just under | ton (Sorlle, 1924) ; stomach of a large blue whale, 

 27-18 m. (89 ft.) long, a little over 8 cwt. (Laurie, 1933; Rammner, 1956). 



Krogh (1934), using the growth curve for blue whales given by Mackintosh and Wheeler (1929) 

 and the length-weight relationship in this species given by Laurie (1933), calculates that in 2 years 

 the southern blue whale grows from a weight of 23,000 kg. at weaning to one of 79,000 kg. at sexual 

 maturity, observing that this enormous increase takes place mainly, if not exclusively, during the 

 two summer seasons (approximately 12 months) the young whales spend in the Antarctic. Walford 

 (1958) estimates that such a growth-rate would require a regular intake of at least no quarts of 

 plankton a day, adding that when the respiratory requirements are added the daily ration would come 

 to 740 quarts. The higher figure would work out at a daily consumption of nearly | ton, for young 

 whales alone. It should be noted, however, that more recent work,^ with improved methods of age 

 determination, indicates that the period from birth to sexual maturity is normally substantially more 

 than 2 years, so that f ton for young whales is likely to be an overestimate, although the observations 

 of Betesheva and Nemoto given below suggest it may not be far out. 



In the stomach of a sei whale Betesheva (1954) reports 600 kg. (about 12 cwl:.) of squid, and a young 

 57-ft. fin is reported (Nemoto, 1959) to have eaten a stomachful of 759 kg. (f ton) of Alaska pollack. 

 Surely the vast stomachs of the adult southern blue and fin whales would hold much greater quantities 

 than these. 



If the fast-growing rat can eat up to 7% of its body weight per day (Donaldson, 1924), a daily 

 ration of i ton does not after all seem an unduly excessive figure for an average-sized, say 60 or 

 70 ton, and also fast-growing, baleen whale, especially when one takes into consideration that it 

 feeds only while in the Antarctic and there perhaps at the outside only for 6 months of the year. 



1 Referring to the stomachs of the southern blue and fin whales Feltmann and Vervoort (1949) remark 'Hierin bevindt 

 zich vaak meer dan 1000 kg. "krill"'. They give no details, however, as to how they arrive at this figure, nor does Douglas 

 (1953) give any authority for his statement that blue and fin whales eat 2-3 tons at a single meal. On the other hand, the 

 1000 kg. mentioned by Schubert (1955) seems to be a very reasonable estimate. It is based on a photograph by Dr Nicolaus 

 Peters of a bulging opened stomach from which the krill in their millions are gushing out. In The Emperor's Nezv Clothes, 

 written on board a whale factory, Hjort (193 1) wrote, 'Thegreat whales we see on the flensing platform Hve on a single species 

 of Crustacea, tons of which may be found in the whale's belly'. I wonder if he really meant tons or was speaking figuratively. 

 Klumov (1961) states that average-sized fin and humpback whales probably eat from i to li tons of plankton per day. 



* See Ruud, Jonsgard and Ottestad (1950). 



