[MARMAM] New publication: Blubber cortisol levels in humpback whales

Mr Fletcher Mingramm fletcher.mingramm at uqconnect.edu.au
Tue Feb 25 17:16:42 PST 2020


Dear MARMAM colleagues,

We are pleased to announce that the following paper is now available online:

Fletcher M.J. Mingramm, Tamara Keeley, Deanne J. Whitworth, Rebecca A. Dunlop,
Blubber cortisol levels in humpback whales (Megaptera novaeangliae): A measure of physiological stress without effects from sampling,
General and Comparative Endocrinology,
Volume 291, 2020, 113436,

Abstract:
Baleen whales are vulnerable to environmental impacts due to low fecundity, capital breeding strategies, and
their reliance on a large amount of prey resources over large spatial scales. There has been growing interest in
monitoring health and physiological stress in these species but, to date, few measures have been validated. The
purpose of this study was to examine whether blubber cortisol could be used as a measure of physiological stress
in humpback whales. Cortisol concentrations were initially compared between live, presumably ‘healthy’ whales
(n = 187) and deceased whales (n = 35), which had died after stranding or entanglement, or washed ashore as a
carcass. Deceased whales were found to have significantly higher cortisol levels (mean ± SD; 5.47 ± 4.52 ng/
g) than live whales (0.51 ± 0.14 ng/g; p < 0.001), particularly for those animals that had experienced
prolonged trauma (e.g. stranding) prior to death. Blubber cortisol levels in live whales were then examined for
evidence of life history-related, seasonal, or sampling-related effects. Life history group and sampling-related
factors, such as encounter time and the number of biopsy sampling attempts per animal, were found to be poor
predictors of blubber cortisol levels in live whales. In contrast, blubber cortisol levels varied seasonally, with
whales migrating north towards the breeding grounds in winter having significantly higher levels
(0.54 ± 0.21 ng/g, p = 0.016) than those migrating south towards the feeding grounds in spring
(0.48 ± 1.23 ng/g). These differences could be due to additional socio-physiological stress experienced by
whales during peaks in breeding activity. Overall, blubber cortisol appears to be a suitable measure of chronic
physiological stress in humpback whales.

An open access copy can currently be downloaded from:

https://authors.elsevier.com/a/1abQm3oGhHjxk

Kind regards,

Fletcher

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