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

Enrico Pirotta*, Robert Schick, Philip Hamilton, Catriona M Harris, Joshua Hewitt, Amy Richardson Knowlton, Scott Kraus, Erin Meyer-Gutbrod, Michael J. Moore, Heather Pettis, Theoni Photopoulou, Rosalind Rolland, Peter Lloyd Tyack, Len Thomas

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

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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.
Original languageEnglish
Article numbere09801
Number of pages15
Issue number5
Early online date6 Feb 2023
Publication statusPublished - 4 May 2023


  • Cumulative effects
  • Multiple stressors
  • North Atlantic right whale
  • Population consequences
  • State space modelling
  • Health


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