High pregnancy rates in humpback whales (Megaptera novaeangliae) around the Western Antarctic Peninsula, evidence of a rapidly growing population.


Journal Article

Antarctic humpback whales are recovering from near extirpation from commercial whaling. To understand the dynamics of this recovery and establish a baseline to monitor impacts of a rapidly changing environment, we investigated sex ratios and pregnancy rates of females within the Western Antarctic Peninsula (WAP) feeding population. DNA profiling of 577 tissue samples (2010-2016) identified 239 males and 268 females. Blubber progesterone levels indicated 63.5% of the females biopsied were pregnant. This proportion varied significantly across years, from 36% in 2010 to 86% in 2014. A comparison of samples collected in summer versus fall showed significant increases in the proportion of females present (50% to 59%) and pregnant (59% to 72%), consistent with demographic variation in migratory timing. We also found evidence of annual reproduction among females; 54.5% of females accompanied by a calf were pregnant. These high pregnancy rates are consistent with a population recovering from past exploitation, but appear inconsistent with recent estimates of WAP humpback population growth. Thus, our results will help to better understand population growth potential and set a current baseline from which to determine the impact of climate change and variability on fecundity and reproductive rates.

Full Text

Duke Authors

Cited Authors

  • Pallin, LJ; Baker, CS; Steel, D; Kellar, NM; Robbins, J; Johnston, DW; Nowacek, DP; Read, AJ; Friedlaender, AS

Published Date

  • May 2, 2018

Published In

Volume / Issue

  • 5 / 5

Start / End Page

  • 180017 -

PubMed ID

  • 29892441

Pubmed Central ID

  • 29892441

Electronic International Standard Serial Number (EISSN)

  • 2054-5703

International Standard Serial Number (ISSN)

  • 2054-5703

Digital Object Identifier (DOI)

  • 10.1098/rsos.180017


  • eng