Conservation challenges and emerging threats to the West Indian manatee (Trichechus manatus) in Florida and Puerto Rico

Abstract

Sirenians are experiencing unprecedented anthropogenic threats around the globe due to habitat destruction, interaction with fisheries, collisions with watercrafts, and climate change. Although the West Indian manatee (Trichechus manatus) has been protected by law for the past five decades, significant threats persist in the United States. In 2017, the US Fish and Wildlife Service (USFWS) downlisted the West Indian manatee from Endangered to Threatened under the Endangered Species Act of 1973 (ESA). Here, we provide an overview of the current conservation status of manatees in US waters, particularly in Florida and Puerto Rico. In recent years, there has been a marked increase in manatee mortalities in the US. The sources of these mortalities are relatively well known, particularly collisions with watercrafts. However, other sources have recently emerged and constitute threats of increasing concern, particularly resource depletion due to seagrass loss and emerging diseases. Recommendations for future research are proposed to improve our understanding of the magnitude of the threats affecting manatees in the US, and support management decisions and conservation actions.