With the construction of the Manuel Moreno Torres hydroelectric plant on the Grijalva river, the ecosystems were modified and the silty-sandy banks used by the river crocodile for nesting disappeared, a situation that caused a slow reproduction of this species. In Tuxtla Gutiérrez, Chiapas, the Miguel Álvarez del Toro Regional Zoo, better known as ZOOMAT, started a program in 1993 to protect the crocodile population that inhabits the Sumidero Canyon area.
In December 1980, immediately after the hydroelectric plant began operations, an area of 30 km along the Grijalva river was declared the Sumidero Canyon National Park. ZOOMAT biologists considered it important to protect and support the conservation of Crocodylus acutus by carrying out different actions in situ and ex situ, such as the collection of wild eggs and hatchlings, reproduction in captivity, the release of animals developed in the zoo and monitoring. continuum of the park's crocodile population. This is how the Crocodylus acutus Baby Release Program was born in the Cañón del Sumidero National Park.
During ten years of work, it has been possible to reintegrate 300 young to their natural habitat, with an estimated survival of 20%. Of these, 235 were born in the ZOOMAT from eggs collected in the park and artificially incubated; a smaller percentage are offspring of the crocodile pair resident in the zoo or collected. Through the monthly censuses in the Sumidero canyon, it has been recorded that the largest and oldest animals released are three nine-year-old crocodiles that in 2004 will become adults, they are thought to be female and their total length exceeds 2.5 meters .
Luis Sigler, researcher in zoology and in charge of this program, indicates that through specific incubation methods they seek to reproduce more females than males in order to promote rapid population growth. During the warmest months of the year, mainly March, they are given the task of locating the nests and taking them to the ZOOMAT facilities; each nest contains 25 to 50 eggs and the females nest once a year. The young are released at two years of age, when they reach a length of 35 to 40 cm. Thus, one and two-year-olds are kept in captivity at the same time, in addition to those that are in the incubation process.
Sigler is optimistic about conservation efforts: “The results are encouraging, we continue to find animals with years of release, which indicates that long-term survival is going well. In daytime monitoring in the study area, 80% of the sightings correspond to tagged animals, which means that the crocodile population has increased substantially, which has direct economic benefits for the communities dedicated to tourism through boat rides through the National Park". However, he warns that little can be done if there is no monitoring structure commensurate with the needs of this important national park.
The Crocodylus acutus is one of the three crocodile species existing in Mexico and the one with the greatest distribution, but in the last 50 years its presence in the historical distribution points has decreased. In Chiapas it currently lives on the coastal plain of the Grijalva River, in the central depression of the state.
