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Daniel-Rentería, I. del Carmen; Serrano, Arturo; Sánchez-Rojas, G.
(detail)
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2012 |
Distribution of the Antillean manatee (Trichechus manatus manatus) in the Alvarado Lagoon System (Veracruz, Mexico).
Ciencias Marinas 38(2): 459-465. 2 figs. June 2012.
–Also ?published as "El Manatí (Trichechus manatus manatus Linnaeus, 1758) (Sirenia) una especie sombrilla, para el Sistema Lagunar de Alvarado, Veracruz", Cuadernos de Biodiversidad No. 33: 16-23, 3 figs., 2010.
ABSTRACT: The Antillean manatee (Trichechus manatus manatus) is considered endangered in Mexico. Local extinctions have been documented in the northern Gulf of Mexico, and the only remaining population with a northern distribution is found in the Alvarado Lagoon System (ALS). The objective of this study was to determine manatee distribution in ALS. The system covers an area of 267,010 ha and includes hundreds of lagoons, floodable areas, and dozens of rivers. To detect manatees, systematic line transects were done in a boat 7.6 m in length, totaling 332.6 h of search effort with an average of 7.38 h d–1 in 45 surveys. There was a total of 13 manatee sightings: seven direct sightings, five with hydrophones, and one with a side-scan sonar. For each record the geographical coordinates were taken and integrated in a geographical information system to analyze their distribution. Manatee distribution was not uniform throughout the study area. Manatees were sighted in very specific areas of ALS considered part of their habitat, mainly in areas with inland water bodies, in some estuarine and marshy areas, and in some wetlands with vegetation generally in appropriate condition. This lagoon system is very important for manatee conservation since it is the last site with viable populations in Veracruz and the northern Gulf of Mexico.
RESUMO: El manatí antillano (Trichechus manatus manatus) es considerado una especie en peligro de extinción en México. En la zona norte del golfo de México se han documentado extinciones locales, y se sabe que la población remanente con distribución más norteña se encuentra en el Sistema Lagunar de Alvarado (SLA). El objetivo de este estudio fue determinar la distribución del manatí en el SLA. El sistema presenta una extensión de 267,010 ha que incluyen cientos de lagunas, áreas inundables y docenas de ríos. La localización de los manatíes se realizó mediante muestreos en transectos lineales sistemáticos en una lancha de 7.6 m de eslora. El esfuerzo de muestreo fue de 332.36 h, con un promedio de 7.38 h d–1 en 45 recorridos. En total se obtuvieron 13 avistamientos de manatíes: siete observados de manera directa, cinco detectados mediante el uso del hidrófono y uno mediante el uso de una ecosonda. En cada registro se tomaron las coordenadas geográficas y se integraron a un sistema de información geográfica para analizar su distribución. La distribución del manatí no se dio de manera uniforme en el área de estudio. Los manatíes se observaron en áreas muy específicas dentro del SLA, consideradas como parte de su hábitat, principalmente en zonas que cuentan con cuerpos de agua interiores, algunas otras áreas estuarinas y palustres, y algunos humedales generalmente con una vegetación en condiciones apropiadas. El SLA es de suma importancia para la conservación de los manatíes, ya que es el último sitio con poblaciones viables en Veracruz y en el norte del golfo de México.
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Serrano, Arturo; Daniel-Renter?a, I. del Carmen; Hernandez-Cabrera, T.; Sanchez-Rojas, G.; Cuervo-L?pez, L.; Bas??ez-Mu?oz, A.
(detail)
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2017 |
Is the West Indian manatee (Trichechus manatus) at the brink of extinction in the State of Veracruz, Mexico?
Aquat. Mamms. 43(2): 201-207. DOI: 10.1578/AM.43.2.2017.201
–ABSTRACT: The West Indian manatee (Trichechus manatus) is distributed from the Atlantic coast of the United States to the center of Brazil along the Atlantic Ocean, Caribbean Sea, and Gulf of Mexico. The species' current distribution is more fragmented than in the past, and manatee populations are generally less abundant than they were during the last century. In Mexico, there is no specific information about the size of the manatee populations. Hence, the objective of this study was to estimate the density and abundance of manatees in the Alvarado Lagoon System (ALS) in Veracruz using distance sampling. In total, 959 systematic line transects were surveyed using a small boat. These surveys covered 90% of the ALS. Manatee density and abundance for the entire ALS was estimated at 0.23 animals/km2 (CV 34.48%) and 121 manatees (CV 34.48%), respectively. These are the first density and abundance estimates for this lagoon system and for the State of Veracruz. The extremely low number of manatees supports the urgent implementation of effective conserva?tion measures for the species to prevent extinction of this species in Veracruz. Key Words: West Indian manatee, Trichechus manatus manatus, abundance, density, Veracruz, conservation, coastal management, Gulf of Mexico, Sirenia
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Bibliography and Index of the Sirenia and Desmostylia 