Gulf of Alaska | Mammals
Pregnancy rates and reproductive hormones in humpback whales Presenter: Shannon Atkinson Demaster , skatkinson@alaska.edu, University of Alaska Heidi Pearson , hcpearson@alaska.edu, Univeristy of Alaska Southeast Suzie Teerlink , suzie.teerlink@noaa.gov, NOAA Fisheries John Moran , john.moran@noaa.gov, NOAA Alaska Fisheries Science Center Kendall Mashburn , klmashburn@alaska.edu, University of Alaska Fairbanks Valentina Melica , valentinamelica88@gmail.com, Univeristy of Alaska Fairbanks
Understanding the reproductive physiology of humpback whales, Megaptera novaeangliae , that reside in Alaska is critical during times of rapid climatic changes. A validated assay for progesterone in free-ranging whales with long-term sighting histories from the waters around Juneau, Alaska was used to ascertain reproductive states in 2020 and 2021. Concentrations of progesterone were highest in the blubber of pregnant (n=4, 30.9 ± 6.7 ng/g in 2020 and n=3, 27.5 + 11.5 in 2021), followed by lactating (n=4, 0.4 ± 0.3 ng/g in 2020 and n=2, 0.5 + 0.3 in 2021) and resting (n=2, 0.4 ± 0.1 ng/g in 2020 and n=4, 0.5 + 0.3 in 2021) female whales. Progesterone concentrations in males (n=13, 0.5 ± 0.2 ng/g in 2020 and n=8, 0.4 + 0.2 in 2021) were also measured. Based on elevated blubber progesterone concentrations, the estimated pregnancy rate among sexually mature females was 0.45 for 2020 (5 of 11 females) and 0.33 for 2021 (4 of 12 females). Of pregnancies predicted based on elevated progesterone, 4 of 5 in 2020 and 2 of 4 in 2021 had calf sightings the following year in Southeast Alaska waters. One female had successive pregnancies for 4 consecutive years. The loss of a pregnancy or calf may be as important as identifying a successful birth when it comes to understanding stressors on the population. Our results demonstrate the synergistic value added when combining immunoreactive assays and long- term sighting histories to further knowledge of reproductive physiology in humpback whales in Southeast Alaska.
Alaska Marine Science Symposium 2023 251
Made with FlippingBook flipbook maker