256 | ANNUAL REPORT SMITHSONIAN INSTITUTION, 1946 
tion has been acquired in recent years on the relative numbers of the 
species and sexes, the constitution of the Antarctic populations, and 
the nature of the changes brought about by the modern whaling in- 
dustry. The large whalebone whales are clearly more abundant in 
the Southern than in the Northern Hemisphere. The oceanic area in 
which suitable conditions exist for the production of their food is 
far greater in the south than in the north, and whaling is carried out 
on an incomparably greater scale. No quantitative comparison has 
been made, but at least the rorquals of the south must presumably 
outnumber those of the north several times over. The sex ratio has 
been examined by Risting (1928), Matthews (1937, 1938b, and Mac- 
kintosh (1942), and although the sexes are nearly equal it seems cer- 
tain that at least in blue, fin, sei, and humpback whales there is a slight 
majority of males in the Southern, and probably also in the Northern 
Hemisphere. This is found not only in the statistics of catches, but 
also in the records of foetuses. Indications are sometimes found of a 
slight tendency toward temporary segregation of the sexes, or local 
variation in the sex ratio. For example, there is generally an excess 
of female humpbacks in the Antarctic catches in summer and of males 
in the tropical catches in winter. The main herds of fin whales which 
appear off South Georgia about midsummer seem at first to include a 
very high proportion of males, but the winter migration of gray 
whales into warmer latitudes is led by a majority of females. 
The catches of the whaling industry give no reliable indication of 
the relative numbers of the different species, for there is too much 
selection in this respect, but observations made by the Discovery 
Committee’s ships, though limited, are more reliable. A good measure 
of agreement was found in the ratio of species seen and identified 
with certainty during voyages of the Discovery IJ and the ratio of 
species marked or shot at by the William Scoresby. This suggested 
that in the Southern Ocean as a whole in summer the existing ratio 
of blue, fin, and humpback whales is of the order of 15, 75, and 10 
respectively (Mackintosh, 1942). Hjort, Lie, and Ruud (1935, etc.) 
have shown that the ratio varies in different parts of the Antarctic, 
largely as a result of whaling, and although allowance is made for 
this the above estimate must be regarded as provisional. Of the other 
species right whales are rare and the sei and lesser rorqual are pre- 
sumably scarcer than the humpback. The lesser rorqual, however, 
is an inconspicuous whale and may be commoner than observations at 
sea would suggest. Little can be said of the Northern Hemisphere 
except that the fin whale predominates in the catches of the modern 
industry. There is no criterion, however, for comparing the relative 
numbers of rorquals and right whales before the latter were reduced 
by the old whaling industry. 
