Alive Antillean manatee stranding is one of the main challenges for the conservation of the species in Brazil. In the present study, data on Antillean manatee stranding recorded by the CMA/ICMBio's Wild Animals Rehabilitation Center from 1987 to 2015 were analyzed. The CMA and the REMANE's (Northeastern Aquatic Mammal Stranding Network's) institutions have rescued on average five Antillean manatees per year. Approximately 56% of the animals were alive when rescued, and 43.7% were found dead. The states of Ceará and Rio Grande do Norte have the highest records of stranding, rescue, and assistance of alive calves. Stranding of alive specimens is more frequent during the austral summer, especially in January, February, and March. In the North region, the main threat to the Antillean manatee population seems to be interaction with fishing activities. Studies on the causes of dependent calf stranding in northeast Brazil are urgently needed to promote the development of public policies for the conservation of the species. Brazil's manatee rehabilitation centers must undergo improvements to better assist stranded calves, which need special care to survive.

The Antillean subspecies of the West Indian manatee is classified as endangered by the International Union for the Conservation of Nature (IUCN) Red List. In Brazil, the manatee population is listed as endangered with an estimated population size of 500–1,000. Historic hunting, recent habitat degradation, and fisheries bycatch have decreased the population size. The Amazonian manatee is listed as vulnerable by the IUCN with unknown population sizes within Brazil. The Antillean manatee occurs in sympatry with the Amazonian manatee in Brazil and hybridization has been previously indicated. To provide information on the genetic structure, diversity, and degree of hybridization in the sympatric zone near the Amazon River mouth, the mitochondrial DNA control region and 13 nuclear microsatellite markers were assessed on the two species. Samples were analyzed from the Antillean subspecies across its distribution in Brazil (n = 78) and from the Amazonian species (n = 17) at the Amazon River mouth and inland mainstem river. To assess the previously defined evolutionary significant units of Antillean manatees in the area, an additional 11 samples from Venezuela and Guyana were included. The Antillean manatee was found to be a single population in Brazil and had lower than average number of alleles (3.00), expected heterozygosity (0.34), and haplotype diversity (0.15) when compared to many other manatee populations. The low values may be influenced by the small population size and extended pressures from anthropogenic threats. Gene flow was identified with Venezuela/Guyana in admixed Antillean Brazil samples, although the two populations were found to be moderately divergent. The nuclear loci in Venezuela/Guyana Antillean manatee samples indicated high differentiation from the samples collected in the Amazon River (FST = 0.35 and RST = 0.18, p = 0.0001). No indication of nuclear hybridization was found except for a single sample, “Poque” that had been identified previously. The distribution of Antillean manatees in Brazil is extensive and the areas with unique habitat and threats would benefit from independent management and conservation actions. Gene flow, resulting in genetic diversity and long-term population stability, could be improved in the southern range through habitat restoration, and the establishments of travel corridors and protected areas, which are particularly important for successful parturition and neonatal calf survival.

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Between September 2001 and March 2013, 62 bacterial cultures (37 aerobic and 25 anaerobic) were performed on 37 blood samples from 23 Antillean manatees ( Trichechus manatus manatus) that were kept in captivity at the Brazilian National Center for Research and Conservation of Aquatic Mammals (CMA) in Pernambuco (CMA-PE) and Alagoas (CMA-AL), Brazil. All of the animals sampled exhibited clinical signs at the time of sampling including abscesses (n = 8), debilitation and anorexia (n = 22), and profound lethargy-moribundity (n = 7). The 4 animals with profound lethargy-moribundity died shortly after sampling of unknown causes. Bacteria were isolated from 15/37 (40.5%) and aerobic blood cultures from 13/23 animals (56.5%). None of the anaerobic cultures were positive. Aeromonas caviae , Aeromonas hydrophila , Aeromonas sp., Escherichia coli , Leclercia adecarboxylata , Pantoea agglomerans , Pseudomonas aeruginosa , Pseudomonas stutzeri , Pseudomonas sp., Sphingomonas paucimobilis , coagulase-negative Staphylococcus, and Staphylococcus epidermidis were each found in only one animal; Staphylococcus spp. was found in two; and Vibrio fluvialis in four. Thirteen samples had only one bacteria isolated, one sample had two bacteria, and one sample had three bacteria isolated. Regarding sex, age group, and origin among the manatees examined, 54.5% (6/11) of the females, 58.3% (7/12) of the males, 40% (2/5) of the calves, 66.7% (8/12) of the juveniles, 50% (3/6) of the adults, 55.5% (10/18) at CMA-PE, and 60% (3/5) at CMA-AL were found to be positive for bacterial growth during at least one sampling time. All Antillean manatees were clinically ill. Regarding clinical signs, bacteria were found in 50% (11/22) of blood samples of the animals showing debilitation and anorexia, 1 of 8 (12.5%) of blood samples of the animals showing abscesses, and 3 of 7 (42.9%) of blood samples of the animals showing profound lethargy-moribundity.

:  We surveyed 13 carcasses of marine mammals (12 Trichechus manatus and one Stenella clymene) that had stranded in northeastern Brazil during 1990-2013 for infectious diseases by screening tissues from the collection of the Brazilian National Center of Research and Conservation of Aquatic Mammal, Chico Mendes Institute for Biodiversity Conservation. Brucella spp. and Mycobacterium spp. were investigated by culturing and PCR of tissue samples, whereas Sarcocystidae parasites, Leptospira spp., and Morbillivirus were surveyed for using specific PCR assays. Brucella spp. and Mycobacterium spp. were not isolated through microbiologic culturing, and all animals were negative for detection of Sarcocystidae parasites, Leptospira spp., Mycobacterium spp., and Morbillivirus by PCR assays. All manatees were negative for Brucella spp. infection, but Brucella ceti was detected in the brain tissue of an S. clymene calf by using a PCR assay.

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Antillean manatees ( Trichechus manatus manatus) are aquatic mammals that inhabit marine waters from Central America to the northeastern region of Brazil, and they are an endangered species. Infection with Toxoplasma gondii through intake of water or food contaminated with oocysts has been reported among marine mammals. The present study aimed to evaluate the prevalence of antibodies to T. gondii in West Indian manatees living in captivity in northeastern Brazil. Serum samples from 55 West Indian manatees from three different captive groups were tested for T. gondii antibodies by means of the modified agglutination test using a cutoff of 1:25. The samples were screened at dilutions of 1:25, 1:50, and 1:500, and positive samples were end-titrated using twofold serial dilutions; antibodies were found in six Antillean manatees (10.9%) with titers of 1:50 in three, 1:500 in one, 1:3,200 in one, and 1:51,200 in one manatee. This study is the first report of T. gondii antibodies in captive Antillean manatees in Brazil.

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.