RELATIVE ABUNDANCE OF SPECIES z6i 



larger numbers than another either because it is more valuable, because the other re- 

 ceives partial protection, and so on. The statistics of catches, however, are helpful in 

 showing variations of the species ratio in different Antarctic areas. 



The catches listed in Table 10, p. 234, cover a long series of years during which changes 

 have occurred in the stocks and in the selection of species by the whalers, and since we 

 are more concerned here with the present or recent condition of the stock it will be 

 convenient for the moment to take the five years preceding the 1938-9 season, for from 

 1938 partial protection of Humpbacks was imposed by international agreement. This 

 period will also correspond with the greater part of the Discovery Committee's relevant 

 data. Right whales may be disregarded since they receive total protection. Sperm 

 whales also may be omitted, since their occurrence in the Antarctic is not representative 

 of the whole stock of that species. Taking from Table 10 the total catches in summer 

 whaling from 1933-4 to ^27'^ and in winter whaling from 1934 to 1938, we get the 

 following figures : 



Blue Fin Sei Humpback 



Total caught 81,598 76,198 1,753 27,638 



Percentage 44 41 J x 4 



Perhaps the only inferences which can be drawn from these figures are as follows. 

 Since Blue and Fin whales were caught in roughly equal numbers, and since Blue whales 

 are more valuable than Fin whales, there must have been a larger number of Fin than 

 Blue whales available during the period in question. Since Sei whales are of little value, 

 and since on account of their more northerly distribution they are not likely to be fairly 

 represented in the Antarctic catches, their existing numbers must be more, and probably 

 considerably more, than 1 % of the total of the four species. Of Humpbacks it can only 

 be said that on the one hand they are less valuable than Blue and Fin whales but on the 

 other hand they are easily caught, and it may be that 14 % is not far from the true pro- 

 portion in which they exist. 



The direct observations from the Committee's ships, and the limitations of the data 

 so obtained, are described above on p. 255. In comparison with the total number of 

 whales seen, the number actually identified as Blue, Fin, Humpback, etc., is quite small. 

 Species can be identified with certainty only at short range and by observers who are 

 thoroughly familiar with their appearance. Even at short ranges there is little to dis- 

 tinguish, say, a Blue whale from a Fin whale except the slight difference in the shape of 

 the dorsal fin. The great majority of whales logged are too far off for this feature to be 

 clearly seen, and it has not generally been the practice for the ship to alter course to get 

 a nearer view of whales seen at a distance, for the numbers noted would hardly then be 

 a random sample of the population. The shape of the spout differs a little in the different 

 species, but this is a very uncertain criterion. It must be affected by the wind, and per- 

 haps also by atmospheric temperature and humidity, and it is doubtful whether even 

 experienced whalers would not be liable to error. Finally, the personal error must be 

 considered, for a constant look-out for whales involves spells of watching by different 

 observers with different degrees of experience. 



