Population dynamics in complex marine environments – a call for process-based models

Marine predators increasingly experience conditions that are unlike those they have encountered in the past, with more wind farms and ships, altered prey availability and increasing temperatures. When we attempt to predict how populations will respond to these entirely novel conditions, statistical extrapolations are likely to fail. Instead, process-based models can yield robust predictions of how populations respond to multiple stressors. In such models, the energetic status, movements and fitness of individual animals can be simulated to reflect changes in environmental conditions and prey availability, allowing population dynamics to emerge as it does in nature. Here we demonstrate how a model framework built for the harbour porpoise (Phocoena phocoena) can predict the cumulative population impacts of wind farms, ship noise, climate change and fisheries. Additionally, we discuss the steps needed to expand the framework to a wider range of marine predators.