Historical reconstruction of the population dynamics of southern right whales in the southwestern Atlantic Ocean

ROMERO, M. A.; COSCARELLA, M. A.; ADAMS, G. D.; PEDRAZA, J. C.; GONZÁLEZ, R. A.; CRESPO, E. A.

Scientific Reports

Springer Nature.

Año: 2022 vol. 12

Understanding the recovery of whale populations is critical for developing population-managementand conservation strategies. The southern right whale (SRW) Eubalena australis was one of thebaleen whale species that has experienced centuries of exploitation. We assess here for the frst timethe population dynamics of the SRW from the southwestern Atlantic Ocean at the regional level tomeasure numerically the efect of whaling and estimate the population trend and recovery level afterdepletion. We reconstructed the catch history of whaling for the period 1670?1973 by an extensivereview of diferent literature sources and developed a Bayesian state-space model to estimate thedemographic parameters. The population trajectory indicated that the pre-exploitation abundancewas close to 58,000 individuals (median= 58,212; 95% CI = 33,329?100,920). The abundance droppedto its lowest abundance levels in the 1830s when fewer than 2,000 individuals remained. The currentmedian population abundance was estimated at 4,742 whales (95% CI = 3,853?6,013), suggestingthat the SRW population remains small relative to its pre-exploitation abundance (median depletionP2021 8.7%). We estimated that close to 36% of the SRW population visits the waters of the PenínsulaValdés, the main breeding ground, every year. Our results provide insights into the severity of thewhaling operation in the southwestern Atlantic along with the population´s response at low densities,thus contributing to understand the observed diferences in population trends over the distributionalrange of the species worldwide.