Density dependence only affects increase rates in baleen whale populations at high abundance levels ...

• Main Authors: Kanaji, Yu, Williams, Rob, Zerbini, Alexandre N., Branch, Trevor A.
• Format: Article in Journal/Newspaper
• Language: unknown
• Published: Zenodo 2024
• Subjects: Bayesian approach; intrinsic growth rate; K-selection; Maximum Net Productivity Level MNPL; Maximum Sustainable Yield MSY; production model; stan; stock assessment; baleen whale; baleen whales
• Online Access: https://dx.doi.org/10.5281/zenodo.12747549; https://zenodo.org/doi/10.5281/zenodo.12747549

Most baleen whale populations are increasing after the end of industrial whaling, but their recovery patterns challenge long-standing assumptions about density dependence. It has long been assumed that population growth rates will decline with recovery, until reaching equilibrium ("carrying capacity", K). Indeed, the International Whaling Commission assumes that growth rates will slow long before K is reached, with maximum productivity at 0.6K. This 0.6K population level is used as an international benchmark that forms the basis of whaling regulations and decisions about whether baleen whale populations are declared depleted. We fit models to four long-term datasets for baleen whales with multiple abundance estimates that span the range from low to high abundance, finding strong evidence that increase rates remain at near-maximal levels across a wide range of abundance levels, and only decline as the population nears K. As a result, maximum productivity occurs at 0.69–0.87 of K across these populations, ...