Manatee Estuarine Complex IMMA

Size in Square Kilometres

120 km2

Qualifying Species and Criteria

West Indian manatee – Trichechus manatus

Criterion A; C (2)

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The distribution of T. manatus is influenced by physiological and environmental factors (water salinity, temperature and depth, and availability of food resources), freshwater supply and anthropogenic habitat modifications. Manatees prefer naturally sheltered areas such as coves, bays and estuaries and are sensitive to disturbance caused by the construction and operation of cities, ports, marinas, shipyards, salt works, shrimp farms and other anthropogenic structures and human activities in these areas. In this manatee estuarine complex IMMA , the necessary ecological requirements for West Indian manatees are found and the relevance of the area becomes even more highlighted, due to its reoccupation by manatees, considering that locally the species was considered extirpated. In 1994, at the beginning of the Manatee Reintroduction Program in Brazil, the rescued and rehabilitated juveniles were released in the states of Paraíba and Alagoas. Over the years, at least seven animals have been identified from sightings, locations issued by satellite transmitters and stranding records, using the Manatee Estuarine Complex IMMA (Souza et al., 2022). In addition, this complex is also used by Guiana dolphins, showing the ecological importance of the IMMA for the conservation of two nationally endangered species of marine mammals in Brazil.

Description of Qualifying Criteria

Criterion A – Species or Population Vulnerability

The West Indian manatee Trichechus manatus is categorized as Vulnerable on the IUCN Red List (Deutsch et al., 2008) and as Endangered on the Brazilian Red List (MMA, 2022). Meirelles et al. (2022) evaluated the extinction risk of the West Indian manatee in Brazil. Although available data on the species abundance and mortality is incomplete to apply the IUCN criteria, the authors worked with limited information following the guidelines for national red-listing, inferring, and projecting based on evidence to produce information and properly evaluate the West Indian manatee risk of extinction. The results indicate that T. manatus is ‘Critically Endangered’ in Brazil due to the extremely high (≥80%) suspected and projected population reduction in the past and the future. Furthermore, although important mortality causes such as hunting were reduced in some parts of the range of the species, other threats are increasing and are not expected to decrease in the coming decades. In the Manatee Estuarine Complex IMMA, the entanglements in fishing nets, and especially collisions with motorized vessels (Borges et al., 2007; Borges et al., 2018) are the main threat factors for the manatees that use this region (Dos Santos, 2020).

Along the Brazilian coast, manatee populations are patchily distributed from Amapá to Alagoas (Luna et al., 2008; de Lima et al., 2011) and there is evidence of released and satellite tagged manatees using the coasts of Sergipe and Bahia States (Deutsch et al., 2008; de Lima et al., 2012; dos Santos et al., 2022).

Criterion C: Key Life Cycle Activities

Sub-criterion C2: Feeding Areas

Dos Santos (2020) characterized the home range areas of six rehabilitated manatees released in this region using satellite and VHF telemetry systems. The results showed manatees exhibited a preference for sites shallower than two meters, with food resources and freshwater availability. The Piauí-Real-Fundo estuarine complex has green and red algae, and seagrasses, whereas only seagrasses were found in the estuary of the Vaza Barris River.

The manatee’s in this IMMA are using areas in the states of Sergipe and Bahia, with a home range of about 42 km2 with two main sites used (data obtained between 2016-2019). In the Vaza Barris River, the animals traveled 14.2 km upstream and 0.4 km from the coast. The main area of use was the estuarine complex of the Piauí/Fundo/Real Rivers, where they traveled 12.6 km upstream (but used these areas with less intensity) and ranged 0.9 km from the coast (Dos Santos et al., 2022; Souza et al., 2022).

Supporting Information

Alves, M.D.O., Kinas, P.G., Marmontel, M., Borges, J.C.G., Costa, A.F., Schiel, N., Araújo, M.E., 2015. First abundance estimate of the Antillean manatee (Trichechus manatus manatus) in Brazil by aerial survey. J. Mar. Biol. Assoc. United Kingdom 96: 1–12. doi:10.1017/S0025315415000855

Aquasis. 2016. Peixe- boi – marinho Biologia e Conservação (1ª ed.) São Paulo – SP: Bambu Editora e Artes Gráficas. 

Borges, J.C.G., Vergara-Parente, J.C., Alvite, C.M.C., Marcondes, M.C.C., Lima, R.P. 2007. Embarcações motorizadas: uma ameaça aos peixes-boi marinhos (Trichechus manatus) no Brasil. Biot Neotrop 7: 199-204. 

Borges, J.C.G., Araujo, V.R., Santos, S.S., Attademo, F.L.N., Normande, I.C., Velôso, M.T.V., Marmontel, M., Vergara-Parente, J.E. 2018. Colisões ocasionadas por embarcações motorizadas em peixes-bois marinhos (Trichechus manatus) no Brasil. XII Congresso da Sociedade Latinoamericana de Especialistas em Mamíferos Aquáticos, Lima, Peru, p. 88.

Carvalho, M. E. S., Fontes, A. L. 2006. Estudo ambiental da zona costeira sergipana como subsídio ao ordenamento territorial. Geonordeste 2: 10-39.

De Lima, R. P., De Alvite, C. M. C., Reid, J. P., Bombassaro Juniro, A. 2012. Distribuição espacial e temporal de peixes-bois West Indian manatees in Brazil (Trichechus manatus) reintroduzidos no litoral nordeste do Brasil. Natural Resources, 2: 63-80.

Deutsch, C.J., Self-Sullivan, C., Mignucci-Giannoni, A. 2008. Trichechus manatus. The IUCN Red List of Threatened Species 2008: e.T22103A9356917. Accessed on 26 January 2023.

Dos Santos, S. S. 2020. Área de vida de peixes-boi marinhos (Trichechus manatus) soltos no Brasil. PhD dissertation. 87 f.

Dos Santos, S. S.; Medeiros, I. S.; Rebelo, V. A.; Carvalho, A. O. B.; Dubut, J. P.; Mantovani, J. E.; Círiaco, R. D.; Dos Santos, R. E. G.; Marmontel, M.; Normande, I. C.; Velôso, T. M. G.; Borges, J. C. G. 2022. Home ranges of released West Indian manatees in Brazil. ORYX, 56 : 1-8.

Fontes, J. A. C. 2010. Caracterização Geoambiental da Sub-bacia do Rio Fundo. PhD dissertation – Universidade Federal de Sergipe. 145 p.

Lima, R. P., Paludo, D., Soavinski, R. J., Silva, K. G., Oliveira, E. M. A. 2011. Levantamento da distribuição, ocorrência e status de conservação do Peixe‐Boi Marinho (Trichechus manatus, Linnaeus, 1758) no litoral nordeste do Brasil. Natural Resources, v: 41‐57.

Luna, F. O.; Lima, R. P. ; Araújo, J. P. ; Passavante, J. Z. O. Status de conservação do peixe-boi marinho (Trichechus manatus manatus Linnaeus, 1758) no Brasil. Revista Brasileira de Zoociências, v. 10, p. 145-154, 2008.

Meirelles, A. C. O., Lima, D. S., Alves, M. D. O., Borges, J. C. G., Marmontel, M., Carvalho, V. L. C., Santos, F. R. S. 2022. Don’t let me down: West Indian manatee, Trichechus manatus, is still critically endangered in Brazil. Journal for Nature Conservation, 67: 1-15.

MMA – Ministério do Meio Ambiente. 2022. Portaria No. 148, de 07 de junho de 2022. Lista Nacional Oficial de espécies da fauna ameaçadas de extinção.

Souza, A. R., Carvalho, A. O. B., dos Santos, S. S., Brito, E. K., Parente, J. E. V., Marmontel, M., Attademo, L. N., Luna, F. O., Lima, R. P., Normande, I. C., Borges, J. C.  G. 2022. Peixes-bois-marinhos (Trichechus manatus) reabilitados usam o litoral de Sergipe e Norte da Bahia, Brasil. IV Simpósio Latinoamericano de Manaties (SILAMA). 19ª Reunião de Trabalho de Especialistas em Mamíferos Aquáticos da América do Sul e XIII Congresso da Sociedade Latino Americana de Especialistas em Mamíferos Aquáticos. Abstract. 2022.


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