Designating critical habitat for juvenile endangered smalltooth sawfish in the United States

Abstract

In 2003, the U.S. distinct population segment of smalltooth sawfish Pristis pectinata was listed as endangered under the U.S. Endangered Species Act (ESA). At that time, little was known about its habitat use patterns and, although required as part of the ESA, critical habitat could not be officially designated. Subsequently, studies were conducted that identified some of the specific habitats and environmental conditions important for the species. Facilitating recruitment into the adult population by protecting the species’ nurseries was identified in the recovery plan as the key conservation objective, which would be supported by the designation of critical habitat. The location of nurseries was determined by applying published criteria developed for identifying elasmobranch nursery areas to a decade of encounter data. These largely nontraditional data were composed primarily of encounters voluntarily reported by the public to members of the recovery team. The nursery habitats essential to the conservation of the species were identified as those adjacent to red mangroves Rhizophora mangle and euryhaline habitats with water depths ≤0.9 m. Ultimately, two broad areas in southwest Florida that contain these habitats were designated as critical habitat for juvenile smalltooth sawfish: the Charlotte Harbor Estuary unit (896 km2) and the Ten Thousand Islands/Everglades unit (2,505 km2).