Once driven to near extinction due to commercial whaling, the Eschrichtius robustus, also known as the gray whale, now stands as one of the success stories of conservation efforts (NOAA). They currently serve as the ‘canary in the coal mine’ to alert scientists of potential environmental changes. Accurate estimation of pregnant and non-pregnant grey whales is an essential milestone in providing more precise reproductive parameters to better understand the population dynamics.
Valentina Melica and her team worked to provide updated insight on the reproductive physiology of gray whales, determining:
- If progesterone and testosterone biomarkers would accurately identify more precise reproduction parameters amongst the population
- If progesterone is an indicator of pregnancy in female gray whales and if it can be used to estimate reproductive status for unknown whales
- Whether progesterone and testosterone showed variation in response to the age, time of year, and geographic location of sampling.
Our DetectX® Testosterone EIA Kit (K032-H) and DetectX® Progesterone EIA Kit (K025-H) were used to measure the testosterone and progesterone concentrations with the intra-assay percent coefficient of variation <10% for both hormones.
The results of the study indicated that testosterone concentrations in males increased with age until they reached maturity, varying by season. It also confirmed elevated testosterone levels during specific seasons, similar to those in other species suggesting a season cycle. In females, it was confirmed that progesterone concentrations are a biomarker for pregnancy and aid in developing a model to estimate the probability of pregnancy amongst female whales of unknown reproductive status. This study provided more accurate estimations critical to continued efforts to understand the reproductive parameters to aid in monitoring and predicting population dynamics.