Manejo para conservação de peixes-bois marinhos (Trichechus manatus LINNAEUS, 1758) no Brasil: programas de soltura e monitoramento

Abstract

The endangered species management can act to reduce population and geographic distribution collapses. Habitat destruction, persecution and environmental change have dramatically reduced the distribution and abundance of many large mammal species. Many of the rarest species now only exist in small, highly disjunct populations with a much higher risk of extinction due to the combined effects of inbreeding depression, loss of genetic diversity and environmental and demographic stochasticity. The adverse effects of small and isolated populations can be mitigated trough the physical translocation of individuals. Focus of one of the longest release and tracking programs in Brazil, the Antillean manatees (Trichechus manatus) are herbivorous aquatic mammals that occurs in coastal and shallow waters from Florida to Alagoas State. Manatees in Brazil area considered as “critically endangered”. The aim of this study was to assess the success rate of the release program and understand the habitat use by released manatees in the north-eastern coast of Brazil. Thirty individuals (18 males and 12 females) were release into two marine protected areas in northeast coast from 1994 to 2012 at a success rate >75%. Time in captivity appears to be a key variable determining post-release success: too long or too short a time in captivity decreasing the probability of survival. Twenty one manatees were radio tagged using GPS and PTT technology. The home range size (Kernel 95%) varied from 4,24 to 30,96 km² (mean = 11,56 ± 8,60). One to six Centres of Activity (COA) were record per animal (mean 2 = 2 ± 2). The COAs size varied from 0,24 to 3,36 km² (mean = 1,36 ± 0,96). Manatees were considered as (1) sedentary or (2) long-distance travellers. The observed home range was apparently lower than other manatee‟s populations. Gender and release site did not show influence on the home ranges. Nevertheless, a clear lesson from the RRMP is that adequate resources are essential. Considerable infrastructure is needed for maintaining captive animals, technology for monitoring released individuals is essential to assess post-release success, and veterinary interventions may be necessary during any phase of the release. It‟s important to increase COAs and travelling corridors protection. This can reduce anthropogenic impacts and augment connection between subpopulations.