. > 30- , - / 1 :â1ââârâââr râ-â D J F MONTHS O N D J MONTHS b M M Text-fig. 48. a, Monthly '% pregnant', South Georgia 1925-31 (full line), pelagic 1932-52 (broken line), b. Monthly frequency of pregnant (full line) and non-pregnant females (broken line) in the South Georgia catches 1927-35. recent ovulations (uncorrected for the active life of the corpus luteum), is then obtained as described above (Text-fig. 47), and the number of recent ovulations observed in each month (column (7)) is obtained by applying these percentages to the estimated number of non-pregnant females in the catch. T
. > 30- , - / 1 :â1ââârâââr râ-â D J F MONTHS O N D J MONTHS b M M Text-fig. 48. a, Monthly '% pregnant', South Georgia 1925-31 (full line), pelagic 1932-52 (broken line), b. Monthly frequency of pregnant (full line) and non-pregnant females (broken line) in the South Georgia catches 1927-35. recent ovulations (uncorrected for the active life of the corpus luteum), is then obtained as described above (Text-fig. 47), and the number of recent ovulations observed in each month (column (7)) is obtained by applying these percentages to the estimated number of non-pregnant females in the catch. The question of the proportion of lactating whales in the monthly samples is discussed in the next section (p. 448), and it is shown that there are relatively large numbers at South Georgia from December onwards, but that very few enter the pelagic grounds until January or February, having weaned the calf before entering colder waters. Those lactating females which do enter the catches are either about to wean, are weaning, or have just weaned, the calf (see below, p. 445). For present purposes lactating females are, therefore, included in the non-pregnant group. Columns (8) and (10) show the estimated numbers of ovulations on the assumption that the corpus luteum is recognizable as such in females taken on the whaling grounds for 15 or 20 days respectively, and in columns (9) and (11) the cumulative frequencies of recent ovulations are shown. If we are correct in postulating that new arrivals to the non-pregnant fin whale female population in the Antarctic ovulate and then enter the true 'resting' state, then the cumulative figures for the number of ovulations should correspond to the build-up of the antarctic population of 'resting females. Unfortunately, we have no data on the actual numbers of animals in the population, but for present purposes we may assume that the monthly catches correspond to the relative abundance in the sea. The catching intensity is probably
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