From archives to conservation: why historical data are needed to set baselines for marine animals and ecosystems
Intergenerational loss of information about the abundance of exploited species can lead to shifting baselines, which have direct consequences for how species and ecosystems are managed. Historical data provide ameans of regaining that information, but they still are not commonly applied in marine conservation and management. Omission of relevant historical information typically results in assessments of conservation status that are more optimistic, recovery targets that are lower, and fisheries quotas that are higher than if long-term data were considered.Here, we review data and methods that can be used to estimate his- torical baselines for marine species including bony fishes, sharks, turtles, and mammals, demonstrate how baselines used in management change when his- torical data are included, and provide specific examples of how data from the past can be applied in management and conservation including extinction risk assessment, recovery target setting, and management of data-poor fisheries. Incorporating historical data into conservation and management frameworks presents challenges, but the alternative—losing information on past population sizes and ecological variability—represents a greater risk to effective manage- ment of marine species and ecosystems.