Physiological effects of research handling on the northern elephant seal (Mirounga angustirostris)

• Published in: Comparative biochemistry and physiology. Part A, Molecular & integrative physiology Molecular & integrative physiology, 2025-01, Vol.299, p.111771, Article 111771
• Main Authors: Cooley, Lauren A., Hindle, Allyson G., Williams, Cassondra L., Ponganis, Paul J., Hannah, Shawn M., Klinck, Holger, Horning, Markus, Costa, Daniel P., Holser, Rachel R., Crocker, Daniel E., McDonald, Birgitte I.
• Format: Article
• Language: English
• Subjects: Aldosterone; Aldosterone - blood; Animals; blood glucose; Blood Glucose - metabolism; Cortisol; erythrocyte sedimentation rate; Female; Heart Rate; Hematocrit; hematology; Hydrocortisone - blood; instrumentation; juveniles; Male; Marine mammals; microprocessors; Mirounga angustirostris; Seals, Earless - blood; Seals, Earless - physiology; species; standard deviation; Stress; stress response; Stress, Physiological; wildlife
• ISSN: 1095-6433; 1531-4332; 1531-4332
• DOI: 10.1016/j.cbpa.2024.111771

Wildlife researchers must balance the need to safely capture and handle their study animals to sample tissues, collect morphological measurements, and attach dataloggers while ensuring their results are not confounded by stress artifacts caused by handling. To determine the physiological effects of research activities including chemical immobilization, transport, instrumentation with biologgers, and overnight holding on a model marine mammal species, we collected hormone, blood chemistry, hematology, and heart rate data from 19 juvenile northern elephant seals (Mirounga angustirostris) throughout a translocation experiment. Across our six sampling timepoints, cortisol and aldosterone data revealed a moderate hormonal stress response to handling accompanied by minor changes in hematocrit and blood glucose, but not ketone bodies or erythrocyte sedimentation rate. We also examined heart rate as a stress indicator and found that interval heart rate, standard deviation of heart rate, and apnea-eupnea cycles were influenced by handling. However, when seals were recaptured after several days at sea, all hormonal and hematological parameters had returned to baseline levels. Furthermore, 100 % of study animals were resighted in the wild post-translocation, with some individuals observed over four years later. Together, these findings suggest that while northern elephant seals exhibit measurable physiological stress in response to handling, they recover rapidly and show no observable long-term deleterious effects, making them a robust species for ecological and physiological research. [Display omitted] •Marine mammal research can be confounded by the stress of capture and handling.•Northern elephant seal physiology was tracked throughout a translocation experiment.•Handling influenced stress hormones, blood chemistry, hematology, and heart rate.•Seals recovered rapidly and exhibited no long-term deleterious effects.