Whiskers as a novel tissue for tracking reproductive and stress-related hormones in North Pacific otariid pinnipeds

Abstract Keratinized tissues, including whiskers, are ideal for acquiring a record of physiological parameters. Most tissues provide snapshot status; however, whiskers may support longitudinal sampling reproductive and stress-related hormones, if hormones incorporated as grow concentrations change with state. Whiskers from female Steller sea lions (Eumetopias jubatus) northern fur seals (Callorhinus ursinus) were serially sectioned pulverized steroid extracted. Standard methods used to validate enzyme immunoassay kits cortisol, progesterone, 17?-estradiol testosterone. All measurable in whisker segments both species progesterone showing cyclical patterns, which appear signify previous pregnancies or luteal phases. Yearly greater years pup was produced compared when no observed. Free-ranging had rates between 0 1.0 (0.53 ± 0.33, n = 12) using yearly concentration 30 pg/mg classify year producing below non-reproductive. Cortisol near the root rapidly declined, lacking any obvious throughout rest whisker. Progesterone testosterone able help determine sex unknown individuals. Immunohistochemistry revealed that most likely do not leach out based on deposition patterns cortisol being present length. Overall, measuring can reveal individual histories over multiple seals. Cyclical ?15N useful identifying periods up ~10 growth within stable isotopes be differentiating active gestation diapause potentially track multi-year otariids.