[MARMAM] New publication: Testosterone Trends In Male Humpback Whales

Kelly Cates kacates at alaska.edu
Fri Apr 12 11:57:48 PDT 2019

Dear colleagues,

My co-authors and I are pleased to announce the publication of the
following article in General and Comparative Endocrinology.

Cates, K. A., Atkinson, S., Gabriele, C. M., Pack, A. A., Straley, J. M., &
Yin, S. 2019. Testosterone Trends Within and Across Seasons in Male
Humpback Whales (*Megaptera novaeangliae)* from Hawaii and Alaska. General
and Comparative Endocrinology.

Understanding reproductive profiles and timing of reproductive events is
essential in the management and conservation of humpback whales (Megaptera
novaeangliae). Yet compared to other parameters and life history traits,
such as abundance, migratory trends, reproductive rates, behavior and
communication, relatively little is known about variations in reproductive
physiology, especially in males. Here, an enzyme immunoassay (EIA) for
testosterone was validated for use in biopsy samples from male humpback
whales. Analyses were conducted on 277 North Pacific male humpback whale
blubber samples, including 268 non-calves and 9 calves that were collected
in the Hawaiian breeding grounds and the Southeast Alaskan feeding grounds
from 2004 to 2006. Testosterone concentrations (ng/g) were significantly
different between non-calves sampled in Hawaii (n = 182) and Alaska
(n = 86, p < 0.05) with peak testosterone concentrations occurring in the
winter (January–March) and the lowest concentrations occurring in the
summer (June–September). Fall and spring showed increasing and decreasing
trends in testosterone concentrations, respectively. Blubber testosterone
concentrations in non-calves and calves sampled in Alaska were not
significantly different. Blubber and skin from the same individual biopsies
(n = 37) were also compared, with blubber having significantly higher
testosterone concentrations (p < 0.05) than skin samples. We found
variability in testosterone concentration with age, suggesting that male
humpbacks reach peak lifetime testosterone concentrations in the breeding
grounds around age 8–25 years. The testosterone profile of male humpback
whales follows a predictable pattern for capital breeders, where
testosterone begins to increase prior to the breeding season, stimulating
the onset of spermatogenesis. Incorporation of reproductive hormonal
profiles into our overall understanding of humpback whale physiology will
shed additional light on the timing of reproduction and overall health of
the recently delisted Hawaii distinct population segment (DPS).

The publication is available at https://doi.org/10.1016/j.ygcen.2019.03.013

Or if you would like a copy sent to you, please email Kelly at
kacates at alaska.edu

*Kelly Cates, PhD Student*
College of Fisheries and Ocean Sciences
Juneau Fisheries Division, University of Alaska Fairbanks
kacates at alaska.edu|

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