. Discovery reports. Discovery (Ship); Scientific expeditions; Ocean; Antarctica; Falkland Islands. THE HUMPBACK WHALE 69 Returning now to Fig. 54 and combining that curve with this, the result shown in Fig. 61 is produced which shows that sexual maturity is reached at the age of about twenty to twenty-two months and that Humpback whales first breed towards the end of their second year. The accuracy of the curve in Fig. 61 formed by joining the curves in Figs. 59 and 60 is upheld by the statement of Olsen (1914-15) that on their southern migration the female Humpbacks are accompanied by calves
. Discovery reports. Discovery (Ship); Scientific expeditions; Ocean; Antarctica; Falkland Islands. THE HUMPBACK WHALE 69 Returning now to Fig. 54 and combining that curve with this, the result shown in Fig. 61 is produced which shows that sexual maturity is reached at the age of about twenty to twenty-two months and that Humpback whales first breed towards the end of their second year. The accuracy of the curve in Fig. 61 formed by joining the curves in Figs. 59 and 60 is upheld by the statement of Olsen (1914-15) that on their southern migration the female Humpbacks are accompanied by calves about 5 m. or more in length and that calves killed off Port Alexander in August were 6-5 m. in length. Engle. Fig. 60. Humpback whale. Average lengths of immature whales by months. (1927), who examined a few Humpbacks in California, suggested that these whales be- come sexually mature while they are yet quite young, a suggestion which is here shown to be correct. The age classes of Humpback whales cannot be deduced from the number of corpora lutea in the ovaries, as can those of the Blue, Fin and Sei whales, because of the shortness of the complete breeding cycle in this species and the indication already shown that pregnancy may sometimes occur twice every three years, or at least that an extra preg- nancy may be interpolated in a more usual two-year cycle. The most that can be said is that the whales with the lowest numbers of corpora lutea (one or two) are in their second year and aged from eighteen months to two years. The classes shown by numbers of corpora lutea after this age may be separated by one and a half years in some cases and two years in others, so that taking into account also the paucity of the data, no indication can be given of the ages of the older whales by this means (cf. Wheeler, 1930).. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustr
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