Variation of bowhead whale progesterone concentrations across demographic groups and sample matrices

Abstract

Bowhead whale Balaena mysticetus progesterone concentrations were measured in different sample matrices (serum, blubber, and urine) to investigate (1) concordance among sample type and (2) variation among life-history class. Samples were collected from subsistencehunted whales (n = 86) taken from 1999 to 2009. In general, irrespective of sample matrix, pregnant females had the highest concentrations by orders of magnitude, followed by mature animals of both sexes, and subadults had the lowest concentrations. Subadult males and females had similar progesterone concentrations in all sample matrices measured. When pregnant animals were included in our analyses, permuted regression models indicated a strong positive relationship between serum and blubber progesterone levels (r 2 = 0.894, p = 0.0002). When pregnant animals were not included, we found no significant relationship between serum and blubber levels (r 2 = 0.025, p = 0.224). These results suggest that progesterone concentrations are mirrored in these sample types over longer periods (i.e. on the order of weeks to months, time frame of reproductive changes) but not shorter periods (i.e. on the order of hours to days, time frame of daily fluctuations). This conclusion is consistent even for progesterone concentrations measured in females that had recently changed pregnancy states (either new mothers or newly pregnant animals), for which blubber progesterone levels seem to lag those in the serum. Finally, urine progesterone had statistically significant positive relationships with serum (r 2 = 0.136, p = 0.0460) and blubber progesterone (r 2 = 0.150, p = 0.0421). Our results suggest that progesterone concentrations first peak in the serum, then in the urine, and finally in the blubber.

Low reproductive success rates of common bottlenose dolphins Tursiops truncatus in the northern Gulf of Mexico following the Deepwater Horizon disaster (2010-2015)

“…Pregnancy determination was based on progesterone concentration, i.e. the mass of progesterone as a fraction of blubber mass (ng g −1 ), using techniques that have been validated for and implemented across numerous cetacean species including bottlenose dolphins (Mansour et al 2002, Kellar et al 2006, 2013a,b, 2014, Pérez et al 2011, Trego et al 2013. Blubber progesterone concentrations were determined as described previously (Trego et al 2013).…”

Fecal glucocorticoids and anthropogenic injury and mortality in North Atlantic right whales Eubalaena glacialis

“…However, methods to measure steroid hormones using alternative matrices (i.e. feces, respiratory vapor, baleen, blubber) have been recently developed for whales (Mansour et al 2002, Rolland et al 2005, Hunt et al 2006, 2014a,b, Hogg et al 2009, Ayres et al 2012, Kellar et al 2013. Measurement of fecal GCs (hereafter fGCs) has been used for decades for stress assessment in terrestrial wildlife, and more recently in marine mammals (reviewed by Keay et al 2006, Amaral 2010, Atkinson et al 2015.…”

Biological matrices for sampling free‐ranging cetaceans and the implications of their use for reproductive endocrine monitoring

“…Recently, progesterone was measured in the serum of bowhead whales Balaena mysticetus taken between 1999 and 2009 by subsistence hunters; progesterone levels were significantly higher in pregnant females than in non‐pregnant females (Kellar et al. ).…”

“…Kellar et al. () suggested the existence of time lags in progesterone levels in blood, urine, and blubber of subsistence‐hunted bowhead whales. Blood and urine progesterone levels appeared to be reflected in blubber over longer periods (weeks to months) but not over shorter periods (hours to days).…”

“…, Kellar et al. ). We hope this review can provide not only basic information on cetacean hormone measurements but also guidance useful to marine mammal researchers for choosing the most suitable techniques and biological matrices, according to the species studied and field conditions for collecting.…”