[MARMAM] New paper on decreasing body size and calving probability in North Atlantic right whales

Enrico Pirotta pirotts at libero.it
Wed Feb 28 08:40:15 PST 2024

Dear MARMAM colleagues,

We are pleased to announce that the following paper is now available online:

Enrico Pirotta, Peter L. Tyack, John W. Durban, Holly Fearnbach, Philip K. Hamilton, Catriona M. Harris, Amy R. Knowlton, Scott D. Kraus, Carolyn A. Miller, Michael J. Moore, Heather M. Pettis, Theoni Photopoulou, Rosalind M. Rolland, Robert S. Schick and Len Thomas. Decreasing body size is associated with reduced calving probability in critically endangered North Atlantic right whales. Royal Society Open Science.

Body size is key to many life-history processes, including reproduction. Across species, climate change and other stressors have caused reductions in the body size to which animals can grow, called asymptotic size, with consequences for demography. A reduction in mean asymptotic length was documented for critically endangered North Atlantic right whales, in parallel with declines in health and vital rates resulting from human activities and environmental changes. Here, we tested whether smaller body size was associated with lower reproductive output, using a state-space model for individual health, survival and reproduction that quantifies the mechanistic links between these processes. Body size (as represented by the cube of length) was strongly associated with a female's calving probability at each reproductive opportunity. This relationship explained 62% of the variation in calving among reproductive females, along with their decreasing health (20%). The effects of decrea!
 sing mean body size on reproductive performance are another concerning indication of the worsening prospects for this species and many others affected by environmental change, requiring a focus of conservation and management interventions on improving conditions that affect reproduction as well as reducing mortality.

Keywords: Bayesian state-space model, body size, capital breeding, Eubalaena glacialis, health, length.

A PDF copy of the paper can be downloaded for free from:


Please do not hesitate to contact me for any question regarding our work.

Best Regards,
Enrico Pirotta
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