328 WHALES 



fluctuations in the composition of krill fat, since experiments on pigs have 

 sho\vn that the iodine number of bacon is largely influenced by their diet. 

 Bacon \\hich is produced on a diet of carbohydrates is more highly 

 saturated, and hence has a lower iodine number, than bacon produced 

 on a fatty diet. Moreover, the iodine number is further influenced by the 

 chemical composition of the particular fat an animal eats. Unfortunately, 

 we do not kno%v sufficient about regional variations of krill fat to come to 

 any definite conclusion on its effects on the iodine number of \vhale-oil. 



A good way to judge the relative fatness of a ^vhale ^vould clearly be to 

 measure the actual thickness of its blubber. We have seen that by express- 

 ing the yield in barrels per B.VV.U., such factors as length and variations 

 in processing from factory ship to factory ship are completely ignored. 

 Now, from the statistics published annually in the Norwegian Hvalfangst 

 Tidende it emerges clearly that the oil output of different factory ships 

 varies greatly. Thus, during the 1955-6 season, factory ships operating in 

 the Antarctic produced an average of 121 -6 barrels per B.W.U., the 

 maximum being 152-1, and the minimum loo-g barrels per B.W.U., and 

 if we look at the individual figures for the past ten years, we see that, while 

 the yield of a given ship varies from year to year, the position of most ships 

 in the list remains fairly constant. Moreover, as the differences in the 

 number of units caught by individual ships have decreased, the differences 

 in the oil output have become more pronounced. 



One of the main reasons for these individual differences between ships 

 is the international catch limit imposed on all ships operating in Antarctic 

 waters. Once the total permissible number of whales has been caught the 

 season is closed, and every expedition tries to get as large a share of the 

 quota as possible for itself. The number and the engine capacity of 

 catchers per factory ship has increased steadily since the Second World 

 War (see Fig. 217), Some of the fluctuations shown in Fig. 2 1 7 are due to 

 the fact that, during some seasons, whaling companies agreed to limit the 

 size of their catcher fleet. The greater the number of catchers the keener 

 the competition, even amongst the boats belonging to one and the same 

 company, with a consequent lack of discrimination in selecting the catch. 

 As a result a greater proportion of the catch consists of small animals and 

 the yield per B.W.U. drops. Furthermore, if a maximum number of whales 

 must be caught and processed in minimum time, whalers may set to work 

 with less attention to detail and a further drop in yield ensues, particularly 

 since dead whales may not be left in the water for more than thirty-three 

 hours. 



Clearly, therefore, the annual statistics published in Sandjeford do not 

 accurately reflect the actual fatness of whales in the different zones or 

 during diflferent seasons, and it is therefore encouraging that the Dutch 



