Measuring steroid hormone levels in the skin of free‐ranging dugongs: A less invasive way to determine reproductive status

Abstract

AbstractMonitoring hormone concentrations in marine mammals provides valuable information regarding reproductive status and health. Skin is potentially useful for measuring hormone levels and can often be collected without capture. We investigated whether progesterone, testosterone, and cortisol could be measured in skin from dugongs using enzyme immunoassays. Hormones were measured in dorsal skin scrapings from free‐ranging dugongs, including known pregnant females, nonpregnant adult females, reproductively active males, and reproductively inactive males, each identified using fecal progesterone or testosterone concentrations. Progesterone could be detected reliably in skin, with significantly higher mean progesterone concentrations (118.2 ± 6.6 ng g−1) in pregnant females than all other groups (60.8 ± 4.2 ng g−1). Male dugongs had higher skin testosterone concentrations than females, although testosterone levels were not detectable in some samples and could not discriminate reproductively active from inactive males. Cortisol was detectable in 8 of 40 skin samples only. Although refinement of this method is required for improved hormone recovery and additional validation is warranted, our findings demonstrate proof of concept for the use of epidermal skin samples to measure steroid hormones in dugongs and offer a method of diagnosing pregnancy in dugongs without the need for capture.