2 o8 DISCOVERY REPORTS 



weights by V = (or for Humpbacks), where D is the greatest height of the 



3 \ 4 / 



body on the flensing platform after removal of the head. Schultz (1938) drew a curve 



based on known weights and deduced a formula which ' may be written 



W = 0-0000269 L 2 ' 789 



when the weight is in kilograms and the length in centimetres '. There must, of course, 

 be a considerable variation in the weight of individual whales of a given length. 



YIELD OF OIL 

 The amount of oil to be obtained from a whale is an important subject, but, like the 

 matter of weight, it will be dealt with here only very briefly on account of the difficulty 

 of obtaining precise data. Whale oil is normally measured by the barrel (equivalent to 

 one-sixth of a ton) and the production of whale oil is usually quoted in terms of the 

 ' Blue-whale equivalent ', in which it is assumed that on the average the yield from a 

 Blue whale is equal to that from 2 Fin, 2I Humpback or 6 Sei whales. This formula is 

 good enough for a rough indication of the average yield from the different species. Thus 

 in the International Statistics, no. xn, p. 13, the average production is given for all 

 seasons in the Antarctic from 1924-5 to 1937-8, and we see that the yield of oil per 

 Blue-whale unit generally varies between about 90 and no barrels. This means that 

 from average whales in the Antarctic about 100 barrels are expected from a Blue whale, 

 about 50 from a Fin, about 40 from a Humpback and about 17 from a Sei. The yield 

 from individual whales must obviously vary very much according to size and physio- 

 logical condition. It also varies according to the efficiency of the technical methods of 

 the whaling industry, and since the oil from different whales is mixed in the factories' 

 tanks without separate measurement it is extremely difficult to assess the average yield 

 of oil from whales of a particular size. The Blue whale equivalent is perhaps as good a 

 formula as can be devised, but inferences should be drawn from it with a good deal of 

 caution, for it is probably not claimed to be quite accurate even as a ratio of the general 

 average yield from the four species. For example, during the Antarctic whaling season 

 the average yield of oil per Blue-whale unit tends to increase from month to month. 

 This undoubtedly is largely caused by the increasing fatness of the whales during their 

 period on the Antarctic feeding grounds. But as the season goes on there is also an 

 increase in the proportion of Fin whales in the catches (see p. 270), and if the yield from 

 an average Fin whale should in fact be a little more than half the yield from an average 

 Blue whale on the Antarctic grounds there would be some increase in the yield of oil per 

 Blue-whale unit even if there had been no increase in fatness. The increased yield is not 

 therefore a reliable criterion of the improved condition of the whales. This element of 

 uncertainty is recognized by Bergersen, Lie and Ruud (1939, p- 13)- 



