432 DISCOVERY REPORTS 



contained no krill but a turbid, watery fluid was present, and this seems compatible 

 with the suggestion that this was a calf which was being fed by the mother but had 

 been starved for two days. In any case it is fairly certain that this 13-35 ^- whale 

 can be safely put down as an unweaned calf. 



Ten days after the capture of No. 1064 another Blue whale (No. 1085) was taken, 

 which measured 13-95 ^^- Here the baleen was still short (22 cm.) and the stomach is 

 noted as containing "a yellow fluid". The baleen seems hardly long enough for inde- 

 pendent feeding and has not yet reached the length at which the increased rate of growth 

 takes place. This may have been the calf of No. 1079, a lactating Blue whale caught the 

 day before. 



These two (Nos. 1064 and 1085) are the two largest unweaned calves of which we 

 have been able to find records. Messrs Hamilton and Matthews, on a visit to Durban 

 in 1926, measured a young Blue whale of 11-85 m. of which the baleen measured 

 15 cm., but there was unfortunately no opportunity to examine the contents of its 

 stomach. 



Unfortunately we met with only one whale measuring between 13-95 m. ^^id i6-o m. 

 and in this whale (No. 823, 15-83 m.) the baleen and stomach were not examined. At 

 16-25 m. No. 248 had baleen 27 cm. long and a substance "like congealed blood" 

 (which may well have been partially digested milk mixed with some blood) in the 

 stomach. The probability is on the whole that this whale had not yet taken to independent 

 feeding. 



Two other whales (No. 767, 16-8 m. and No. 1584, 16-95 "■>•) both had krill in the 

 stomach. The baleen was not measured in these whales but in No. 1 104 which measured 

 16-82 m. (and had only blood in the stomach) the baleen was 40 cm. long, suggesting 

 that this whale had also been weaned. 



It is thus reasonably certain that weaning takes place when the calf has reached some 

 length between about 14-0 m. and 16-5 m. In view of the fact that No. 248 measuring 

 16-25 ™- was probably not weaned, and that the growth of the baleen plates appears 

 to become speeded up between 16-0 m. and 17-0 m. it is probable that the required 

 length is much nearer 16-5 m. than 14-0 m. Now, although No. 248 appeared not to 

 be weaned it will probably be safest to put the mean length at which Blue whales are 

 weaned at i6-o m. for there is likely to be plenty of variation in the length of the calf 

 at this stage and we have three whales from 16-8 m. to 16-95 "^- which were all 

 weaned. 



Fin whales are evidently weaned at a much shorter length than Blue whales. The 

 smallest specimen we examined measured 12-3 m. (No. 891) and had krill in the stomach 

 and baleen 41 cm. long. Krill was also present in No. 999 (13-35 ^^•) but the baleen 

 was not measured. In No. 910 (13-38 m.) the stomach was empty, but in No. 84 

 (13-55 "^0 ^ milk-like substance was present in the stomach and the baleen measured 

 30 cm. In No. 1187 (also 13-55 n^-)* on the other hand, the baleen measured 50 cm. 

 and though the stomach contents were not examined the faeces were typical of whales 

 feeding on krill. 



