Biomarkers from feces, blow and baleen give new windows into whale physiology and stress

Kathleen Hunt reviewed biomarkers and alternative sample matrices that can be obtained from baleen whales and explained their temporal resolution: blow/respiratory vapor reflects near‑instantaneous state, feces reflect approximately the prior day, baleen records a multi‑month to multi‑year time series, and blubber provides tissue‑level signals. "A hormone is a messenger molecule released into the blood by an organ to talk to the other organs in the body...the hormones are the internal signal that causes an animal to change physiological states," Hunt explained.

Hunt summarized empirical findings from long‑term fecal hormone monitoring of the Pacific Coast Feeding Group: models detected a faint but consistent signal linking anthropogenic disturbance and elevated fecal cortisol one day later, and fecal hormone concentrations in prior years were associated with the probability a female would calve two years later. She also described baleen hormone records that in several whales showed rising stress hormone deposition about nine months before death, suggesting baleen can provide retrospective timing of prolonged physiological deterioration.

The talk reviewed practical tradeoffs—earwax plugs can record life‑long histories but are time‑intensive to process and not always collected; respiratory vapor is low‑volume but repeatable; baleen provides fine temporal sequences but growth rates and segment dating require calibration. Hunt and colleagues flagged vitreous humor from eyeballs as a promising matrix for decomposed necropsy specimens.