The future of baleen whales: Recoveries, environmental constraints, and climate change

Most baleen whales were severely overexploited during the past century, but many populations have received near-complete protection from exploitation for more than a half-century. Some of these populations have made remarkable recoveries and are now approaching pre-exploitation levels of abundance. Contrary to expectations of baleen whales making minor oscillations around equilibrium abundances, several populations that have made the strongest recoveries have experienced major mortality events. We review examples from the literature showing increasing demographic variability in recovering populations of baleen whales and present a simulation study on the expected response of recovered versus depleted whale population to environmental variability and climate impacts. We propose that baleen whales are more sensitive to environmental variability than previously recognized; that major demographic fluctuations will become the norm as baleen whales recover; and that climate-driven disruptions to whale population dynamics will be most dramatic in populations with the lowest rates of anthropogenic mortality.