A promising tool to infer the protein balance and reproductive status of the capital breeding southern right whale
Geraldine Busquets-Vass, Emma l. Carroll, Nico L?bcker, Rochelle Constantine, Simon Childerhouse, Scott Baker, Glenn Dunshea, Mark Hindell, Seth D. Newsome
Understanding the reproductive physiology of baleen whales, such as the endangered southern right whale (SRW), is a key element for evaluating how environmental change may impact their fitness. We developed a novel method to assess protein balance in response to reproduction that uses carbon and nitrogen isotope analysis of amino acids (AA) in skin tissue. We analysed biopsy samples from 27 cows, 24 calves, 15 adult females without calves, and 19 adult males collected from SRW between 2003?2020 during the wintering breeding season around the mainland of New Zealand and the sub-Antarctic Auckland Islands; 24 of the calf samples were paired with cow genetically confirmed to be their mothers. Linear discriminant analysis (LDA) of AA ?15N and ?13C values separately shows that cows and calves can be correctly classified with 87% and 74- 75% success rate, respectively. In contrast, both ?15N and ?13C values of both bulk tissue and its constituent AA did not differ between adult females without calves and adult males, suggesting protein balance in these demographic classes is similar. This classification method could be used to identify periods of reproduction along baleen plates or other metabolically inert tissues in capital breeding mammals.