Historical ecology reveals the “surprising” direction and extent of shifting baselines for the Florida manatee (Trichechus manatus latirostis)

Abstract

Historical data are often overlooked in risk assessments and recovery plans for marine animals, resulting in the “shifting baselines.” Historical ecological studies demonstrate the “surprising” extent to which contemporary assumptions misrepresent premodern baselines. The Florida manatee, a subspecies of the West Indian manatee found primarily in Florida, USA, faces several existential threats, but risk assessments and recovery targets for the species are hindered by poor understanding of historical baselines. We conducted systematic and opportunistic reviews of archaeological and historical records of manatee occurrence in Florida, USA. Our data reveal that manatee populations in Florida were very small in the Precolonial and Colonial Periods, possibly representing infrequent in-migration from the Caribbean during favorable climate conditions. Manatees expanded in number and range across the Florida peninsula during the Territorial/Early Statehood and Early Modern Periods, first northward on the Atlantic Coast and later along the coast of the Gulf of Mexico. These expansions track increasing human populations, associated anthropogenic landscape alterations, and social and policy changes. Historical ecology is critical for “shaping a better Anthropocene” for humans and manatees in Florida.