Determination of Age in the Humpback Whale, Megaptera nodosa (Bonnaterre)

Abstract

The use of baleen, ear plugs, and ovaries in the determination of age in humpback whales is described.

From the evidence of baleen, the majority of humpback whales reach puberty at 4 or 5 years of age.

The rate of accumulation of laminations in ear plugs is two laminations per year. The mean rate of ovulation in sexually mature females is 1.1 per year. Age determination upon the same sample of mature females by these two methods gives very similar distribution of ages.

The age distribution within separate sexes from samples of mature humpback whales examined on the west and east coasts of Australia in 1957 are compared. The results indicate that the population migrating along the west coast is at present composed of younger individuals than that on the east coast of Australia.