Hervey Bay humpbacks reach most of their adult length by about age seven

Eastern Australian humpback whales reach about 10.9 metres, or 36 feet, by age five, and about 90 percent of adult length by roughly six or seven. Phys.org reported the finding on October 22, 2026, from a paper in Marine Mammal Science. Stephanie Stack, a doctoral researcher at Griffith University working with the Pacific Whale Foundation, built the growth curves from drone photogrammetry and photo identification. The set covers 865 identified whales, from calves to adults older than 40, photographed between 2021 and 2024.

Stack said the early growth is faster than in other humpback populations measured this way. The curves are the first contemporary ones drawn from living animals, rather than from whaling-era records. Adult lengths still match historical estimates for Australian humpbacks, even after the population's recovery. Growth is fastest in the early years and then slows. The paper is a baseline for size, not a new population count, and it does not itself show how the whales are responding to a changing ocean. That comparison is work for later seasons.