Blow Collection as a Non-Invasive Method for Measuring Cortisol in the Beluga (Delphinapterus leucas)

Abstract

Non-invasive sampling techniques are increasingly being used to monitor glucocorticoids, such as cortisol, as indicators of stressor load and fitness in zoo and wildlife conservation, research and medicine. For cetaceans, exhaled breath condensate (blow) provides a unique sampling matrix for such purposes. The purpose of this work was to develop an appropriate collection methodology and validate the use of a commercially available EIA for measuring cortisol in blow samples collected from belugas (Delphinapterus leucas). Nitex membrane stretched over a petri dish provided the optimal method for collecting blow. A commercially available cortisol EIA for measuring human cortisol (detection limit 35 pg ml−1) was adapted and validated for beluga cortisol using tests of parallelism, accuracy and recovery. Blow samples were collected from aquarium belugas during monthly health checks and during out of water examination, as well as from wild belugas. Two aquarium belugas showed increased blow cortisol between baseline samples and 30 minutes out of water (Baseline, 0.21 and 0.04 µg dl−1; 30 minutes, 0.95 and 0.14 µg dl−1). Six wild belugas also showed increases in blow cortisol between pre and post 1.5 hour examination (Pre 0.03, 0.23, 0.13, 0.19, 0.13, 0.04 µg dl−1, Post 0.60, 0.31, 0.36, 0.24, 0.14, 0.16 µg dl−1). Though this methodology needs further investigation, this study suggests that blow sampling is a good candidate for non-invasive monitoring of cortisol in belugas. It can be collected from both wild and aquarium animals efficiently for the purposes of health monitoring and research, and may ultimately be useful in obtaining data on wild populations, including endangered species, which are difficult to handle directly.

An Economical Custom-Built Drone for Assessing Whale Health

“…Sampling exhaled breath or 'blow' from wild whales may therefore provide a more representative assessment of the health status of individuals because samples can be randomly taken from the population. From a single sample of whale blow, scientists may be able to collect respiratory bacteria, lipids, proteins, DNA and hormones (Hogg et al, 2005(Hogg et al, , 2009Schroeder et al, 2009;Acevedo-Whitehouse et al, 2010;Hunt et al, 2013Hunt et al, , 2014Thompson et al, 2014;Burgess et al, 2016;De Mello and De Oliveira, 2016;Raverty et al, 2017). This information is important for whale conservation, as it can be collected over time to help monitor the recovery of whale populations postwhaling.…”

Cortisol levels in beluga whales (Delphinapterus leucas): Setting a benchmark for Marine Protected Area monitoring

“…Cortisol has been used as an indicator of stress response and overall population health for a wide range of mammals (Sheriff et al 2011;Atkinson et al 2015). It has been quantified in many matrices such as blood (serum/plasma), urine, feces and hair, as well as in blubber and the blow from cetaceans (St. Aubin et al 2001;Schmitt et al 2010;Macbeth et al 2012;Palme et al 2013;Thompson et al 2014;Kellar et al 2015;Trana et al 2015). Cortisol has also provided insight into stress associated with contaminants, such as persistent organic pollutants (POPs) that include PCBs and PBDEs (Verboven et al 2010;Bechshoft et al 2012b).…”

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“…All solutions were prepared according to the manufacturer`s instruction. The assay validity for fish cortisol has been reported to be comparable to Cayman Cortisol Assay Kit [20]. Cortisol standards were used to generate the standard curve.…”