Dear colleagues, On behalf of all co-authors, I hereby share a new paper recently published on southern right whale baleen endocrine profiles. ABSTRACT Gestation length is a key reproductive parameter influencing fecundity, population growth rates, and the recovery potential of baleen whales. However, direct knowledge of the gestation length in these large mammals remains limited, primarily inferred from whaling and observational data. Over the past decade, southern right whales have experienced a decline in reproductive success, likely linked to climate-change-induced shifts in foraging conditions. Understanding the population-level consequences of these changes requires detailed longitudinal reproductive data. This study analyzes multiyear steroid hormone profiles in the baleen of adult female southern right whales stranded along the South African coast. Results show an extended hormonal pattern characterized by two peaks in progestogens between 20 and 25 months—suggesting putative pregnancies lasting substantially longer than previous estimates. Sharp estrogen peaks during periods of elevated progestogen phases may indicate hormonal regulation of myometrial contractions at birth. A positive correlation between progestogens and glucocorticoids suggests a role for glucocorticoids in pregnancy maintenance, while androgens provide limited insight into female reproduction in this species. These findings imply a longer-than-expected gestation period for southern right whales and potentially across the balaenid family. This has important implications for understanding the timing and location of conception, relevant for conservation management strategies. Multipopulation studies alongside individual sighting histories are recommended to refine our understanding of southern right whale reproduction further. The paper is open access and available at https://onlinelibrary.wiley.com/doi/10.1002/ece3.71528 With kind regards, Els Dr Els Vermeulen Senior Lecturer and Research Manager Mammal Research Institute Whale Unit Faculty of Natural and Agricultural Sciences University of Pretoria, South Africa +27 (0)60 9714301 / els.vermeulen@up.ac.za https://www.mammalresearchinstitute.science/whale-unit “For the love of whales, for the future of our oceans” -- This message and attachments are subject to a disclaimer. Please refer to http://upnet.up.ac.za/services/it/documentation/docs/004167.pdf <http://upnet.up.ac.za/services/it/documentation/docs/004167.pdf> for full details.