Estimating the effects of stressors on the health, survival and reproduction of a critically endangered, long-lived species

• Published in: Oikos
• Main Authors: Pirotta, Enrico, Schick, Robert, Hamilton, Philip, Harris, Catriona M, Hewitt, Joshua, Knowlton, Amy Richardson, Kraus, Scott, Meyer-Gutbrod, Erin, Moore, Michael J., Pettis, Heather, Photopoulou, Theoni, Rolland, Rosalind, Tyack, Peter Lloyd, Thomas, Len
• Other Authors: University of St Andrews.School of Biology, University of St Andrews.Centre for Energy Ethics, University of St Andrews.Office of the Principal, University of St Andrews.Scottish Oceans Institute, University of St Andrews.Centre for Research into Ecological & Environmental Modelling, University of St Andrews.Sea Mammal Research Unit, University of St Andrews.School of Mathematics and Statistics, University of St Andrews.Institute of Behavioural and Neural Sciences, University of St Andrews.Statistics, University of St Andrews.Marine Alliance for Science & Technology Scotland
• Format: Article in Journal/Newspaper
• Language: English
• Published: 2023
• Subjects: Cumulative effects; Multiple stressors; North Atlantic right whale; Population consequences; State space modelling; Health; QL Zoology; Ecology; Evolution; Behavior and Systematics; DAS; MCC; QL; Eubalaena glacialis; North Atlantic
• Online Access: https://hdl.handle.net/10023/26925; https://doi.org/10.1111/oik.09801

Funding: Office of Naval Research (Grant Number(s): N000142012697, N000142112096); Strategic Environmental Research and Development Program (Grant Number(s): RC20-1097, RC20-7188, RC21-3091). Quantifying the cumulative effects of stressors on individuals and populations can inform the development of effective management and conservation strategies. We developed a Bayesian state–space model to assess the effects of multiple stressors on individual survival and reproduction. In the model, stressor effects on vital rates are mediated by changes in underlying health, allowing for the comparison of effect sizes while accounting for intrinsic factors that might affect an individual's vulnerability and resilience. We applied the model to a 50-year dataset of sightings, calving events and stressor exposure of critically endangered North Atlantic right whales Eubalaena glacialis. The viability of this population is threatened by a complex set of stressors, including vessel strikes, entanglement in fishing gear and fluctuating prey availability. We estimated that blunt and deep vessel strike injuries and severe entanglement injuries had the largest effect on the health of exposed individuals, reinforcing the urgent need for mitigation measures. Prey abundance had a smaller but protracted effect on health across individuals, and estimated long-term trends in survival and reproduction followed the trend of the prey index, highlighting that long-term ecosystem-based management strategies are also required. Our approach can be applied to quantify the effects of multiple stressors on any long-lived species where suitable indicators of health and long-term monitoring data are available. Peer reviewed