Steroid hormone profiles and body conditions of migrating male humpback whales (Megaptera novaeangliae)

• Published in: General and Comparative Endocrinology
• Main Authors: Dalle Luche, Greta, Boggs, Ashley SP, Kucklick, John R, Hawker, Darryl W, Wisse, Jillian H, Nash, Susan Bengtson
• Format: Article in Journal/Newspaper
• Language: English
• Published: Elsevier BV 2021
• Subjects: Biological oceanography; Medical physiology; Zoology; Veterinary sciences; Clinical sciences; Humpback Whale; Megaptera novaeangliae
• Online Access: http://hdl.handle.net/10072/407421; https://doi.org/10.1016/j.ygcen.2021.113888

Simultaneous analysis of multiple steroid hormones from remotely obtained blubber biopsies has the potential to concurrently provide information regarding stress and reproductive status from free-swimming cetaceans, while also investigating correlations between hormone concentrations and other health biomarkers. In this study we measured blubber concentration profiles of eight reproductive and adrenal steroid hormones (17α-hydroxy-progesterone, testosterone, androstenedione, progesterone, cortisol, 11-deoxy-corticosterone, oestrone, and oestradiol) together with body condition, as determined by the inverse Adipocyte Index, of 101 male humpback whales. Whales were sampled randomly at two time points, while migrating to and from their northeast Australian breeding grounds, allowing for intra- and inter-seasonal profile analysis. Testosterone, progesterone and cortisol together with androstenedione 17α-hydroxyprogesterone, and oestrone concentrations (the latter quantified for the first time in live biopsied male humpback whales) decreased between the northward and southward migrations. Decreasing testosterone levels during the height of humpback whale conceptions suggests asynchronicity between blubber testosterone levels and the expected peak of male fertility. Statistically significant relationships between levels of certain steroid analytes were observed and appeared to change between the early and late breeding seasons. During the northward migration, testosterone, progesterone, androstenedione, oestrone and 17α-hydroxyprogesterone levels were positively correlated. Cortisol concentrations correlated positively with those of testosterone during the northward migration, but negatively during the southward migration. Androstenedione and testosterone were positively correlated with adiposity during the late breeding season. These hormone-hormone and hormone-adiposity correlations may be reflective of the activation of certain steroid hormone synthesis pathways, or alternatively, of concomitant physiological ...