Manatees in Mexico: research and conservation in the
Catazajá wetlands, Chiapas
Jenner Rodas MSci., Project coordinator Emilio Romero Berny, BSci. Research
assistant Departamento
de Vida Silvestre, Subsecretaría de Medio Ambiente Desarrollo Urbano y Vivienda
del Estado de Chiapas
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Alejandro Estrada, Ph.D, collaborating scientist Estación de Biología Tropical Los Tuxtlas, Instituto de Biología, Universidad Nacional Autónoma de México |
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Texts prepared by Jenner Rodas, Emilio Romero Berny y Alejandro Estrada; Photo credits J. Rodas, E. Romero Berny y A. Estrada, except photo top right (credit: USGS-Sirenia Project) and 4 below the map (credit: freeweb, Wikipedia, http://www.homesafe.com/manatee/photographs/index.html)
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Manatees (Order Sirenia, family Trichechidae,
genus Trichechus)
are large, fully aquatic marine mammals sometimes known as sea cows. The Sirenia is thought to have evolved from four-legged land mammals
over 60 million years ago, with the closest living relatives being the Proboscidea (elephants) and Hyracoidea
(hyraxes). Manatees inhabit the shallow, marshy coastal areas
and rivers of the Caribbean Sea and the Gulf of Mexico (T. manatus, West Indian Manatee), the Amazon Basin (T.
inunguis, Amazoninan
Manatee), and West Africa (T. senegalensis,
West African Manatee). A fourth species, the Dwarf Manatee (T. bernhardi) was recently proposed for a population
found in the Brazilian Amazon (text from WIkipedia). Left: Approximate geographic
distribution of Trichechus; T. manatus
in green; T. inunguis in red; T. senegalenis in organge (map
from Wikipedia: http://en.wikipedia.org/wiki/Manatee). |
Manatees are mainly herbivores consuming about 10% of their body weight
per day. They spend most of their time grazing in shallow waters and at depths
of 1-
In Mexico the manatee is found along the
coast of the Gulf of Mexico and in the Caribbean coastline of the Yucatan
peninsula, and it is represented by the subpsecies Trichecus manatus manatus. The manatee is considered a species in danger
of extinction in
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Left: location of the Catazajá wetlands in the state of
Chiapas, México. These wetland area is found about |
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The name Catazajá comes from the Mayan
language spoken in the rea. “Kaa” means valley; “tasal”
means flatland and “ja” means water[ Catazajá: "valley covered with water". Human population in
Catazajá consists of descendants of indigenous Mayan people and people of
Spanish descent. Their subistence economy consists
mainly of finishing and agriculture as well as cattle ranching in the higher
elevations. Eco-tourism is a new development and it is foreseen to intensify
as a result of government promoted conservation activities in the wetlands. |
Mapping
and monitoring of the manatee population
Three complimentary methods are used to map the distribution of the
manatee in the Catazaja wetlands: direct sightings from a boat as manatees come up to the surface for air
and detection of water surface movements of individuals, indirect indication of
presence and activity of manatees by noting the presence of aquatic vegetation
on the water surface that had evidence of having been recently browsed by
manatees.
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Use of sonar
systems to detect manatees underwater In addition to the above recording methos, presence of manatees underwater is also recorded
using a side-scan sonar system. This method allows for additional
information, including the possibility of classifying the manatees by their
size into broad age classes (adults, subadults,
juveniles, recently born). It also provides information on ther swiming velocity and
direction as well as on environmental parameters such as water temperature at
various depths, among others. |
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Tracking movements
of manatees in the wetlands Some manatees are captured with the aim of placing radiotransmitters in their caudal fin. Tracking the
signal emitted by the transmitter provides information on the amplitude of
daily and seasonal movements of manatess in the
wetland system, allowing us to understand how they use their habitats. Left: Radiocollar (antena,
collar and power sourcer) used to track movements
of manatees; Right,
adult manatee with radiocollar placed around its
tail before being released into the water – note the while standing antena. |
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Other
records of presence of manatees
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Additional information of evidence of
presence of manatees in the wetlands is obtained by detecting recently
browsed acquatic vegetation (left photo), by the ocassional discovery of carcasses (center photo) and by the rare
discovery of skeletal remains (extreme
right photo). |
Incorporation of local communities in the conservation of manatees and
their habitats
Through various structured initiatives we have
gradually involved the local communities in the conservation of manatees and
the wetland ecosystem. While these initiatives are still in progress, tangible
outcomes of community involvement in conservation are the following: protection
by the local community of manatee preferred gathering areas in the wetland is
gaining strength, hunting of manatees is now almost non existent, local people
trained by us now assist in keeping track of manatee sightings and local
community members actively become involved in the rescue of stranded
individuals. Importantly, the manatee has now become the animal emblem for the
communities. A manatee festival is held once a year, with intensive
participation by local inhabitants, including adults of all ages and school
children
Rescue
of stranded manatees
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While being rescued, manatees are
measured, weighed, photographed and checked for several clinical features
(e.g. wounds, parasites, etc) and other aspects. This information importantly
adds to the databanks on the manatees' biology, ecology and behavior. Photo upper extreme left: baby manatee being rescued. Other photos show
rescue of adult manatees. |
Other fauna found in the Catazajá wetlands
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The Catazajá wetland subsystem is an
extensive flooded flatland encompassing about 60,000ha. It contains 112 seasonal
and 10 permanent lagoons as well as several streams and small rivers that
traverse its flatlands and the edges of these are populated by a mixture of
aquatic and rainforest vegetation. The wetlands are particularly rich in
aquatic and terrestrial wildlife. There are about 164 bird species (many of
these migratory), aquatic mammals such as the manatee and river otter (Lontra longicaudis),
terrestrial mammals such as the black howler monkey (Alouatta
pigra) and felids such as the Ocelot (Felis pardalis).
Reptiles such as Moreletti’s crocrodyle (Crocodylus
moreletti), the green iguana (Iguana iguana) and the white turtle (Dermatemys
mawii) are common in the wetlands. Conservation of manatee populations in the Catazajá
wetlands is closely linked to the conservation of the wetland ecosystem as a
whole. |
Recent Publications:
Rodas-Trejo, J., Romero-Berny,
E. I. and Estrada, A. 2008.
Distribution and conservation of the West
Indian manatee (Trichechus manatus manatus) in the Catazajá wetlands of northeast
Acknowledgements: Agradecemos el
apoyo, colaboración y asesoría en el proyecto brindados por el Dr. David León
Olivera y el M en C. Darwin Jiménez, de
For further infrormation on this project and internships please contact one of the following: M en C. Jenner Rodas Trejo <jennerodas@hotmail.com>, Biol. Emilio Romero Berny <romeroberny@gmail.com>, Dr. Alejandro Estrada aestrada@primatesmx.com
copyright@primatesmx.com