Meeting Abstract
Whale earplugs are known to store lipophilic hormones and chemical information over the life of the individual. During this study we investigated changes in progesterone levels in the cerumen of five species of baleen whales (N=12) from the early 1900s to present day: fin whales (N=5), humpback whales (N=3), blue whales (N=2), minke whales (N=1), and bowhead whales (N=1). Laminae within each earplug are accreted into light and dark bands and are estimated to correspond to one year of life of the whale. After laminae were dissected from the earplug, lipids were extracted and assayed for the hormone progesterone which was used as a proxy for pregnancy occurrences. Peaks in progesterone were identified and overall relative percent change among lamina was calculated in order to estimate pregnancies. Furthermore, laminae progesterone concentrations and potential pregnancy events were compared with known sightings of female and calf. Minimum progesterone concentration detected was 0.03 ng/g and maximum was 20.8 ng/g. Inter-pregnancy intervals for all whales combined was 3.6 years, for fin whales 3.1 years, for humpback whales 4.0 years, for blue whales 4.8 years, for minke whales 4.4 years, and for bowhead whales 3.4 years. Average pregnancy rate per year for all whales was 0.22. Using whale earplugs to estimate lifetime pregnancy occurrences is a powerful tool which can be used in order to compare pregnancy rates and intervals from the early 1900s to present day to birth rates and inter-calving intervals.
