Reproductive success of Antillean manatees released in Brazil: implications for conservation

Abstract

Actions to rescue, rehabilitate and release calves of manatees are the main initiatives and strategies for conservation of the species in Brazil. The survival rate of animals in a natural environment and the reproductive success, identified by birth records, are some of the indicators used to estimate the release success for manatees. This study evaluated the effectiveness of releases of West Indian manatees based on the reproductive success of rescued animals that were released back into the wild in Brazil. Twenty-two female manatees were released in the states of Alagoas (into an extinct area) and Paraíba (into an existent population) from 1994–2020. Six females gave birth to 13 calves, all in Alagoas State. The average age of the first calving event was 11.7 (±1.49) years and 8.0 (±1.41) years after release. Among the females that had more than one calving, the average was 3.6 (±1.18) years between each calving. All calves observed were born alive; nevertheless, three (23.1%) died a few weeks after birth. In general, females rehabilitated in captivity and released in the wild were able to reproduce, especially in protected areas. This study emphasizes the need to intensify actions for the conservation of manatees and their habitats in order to achieve healthier wild populations.