Pond Dynamics/Aquaculture CRSP

Aquanews ~ Winter 2001

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by Wilfrido M. Contreras Sánchez and Gabriel Márquez Couturier

Farmers from Ejido Rio Playa, Tabsco, Mexico, collecting juvenile tilapia and gars, used to stock grow-out earthen ponds

The Laboratory of Aquaculture of the Biological Sciences Division at the Universidad Juárez Autónoma de Tabasco (UJAT) has played an important role in promoting aquacultural development in Mexico. Founded in the early ‘90s the laboratory has focused on training students and technicians and on generating scientific information about the biology and culture of native and introduced species with potential for aquaculture in the region.

Three main research thrusts have guided the laboratory: 1) food production; 2) ornamental production; and 3) restoration and enhancement. The philosophy of the laboratory is centered on developing sustainable aquaculture under the principles that rule UJATs mission: Education, Research, and Outreach. Efforts have aimed toward the development and transfer of technologies for small-scale fish farmers with the intention of increasing their income and ultimately their food supply.

In 1999 UJAT joined the PD/A CRSP through a collaborative research effort between Oregon State University (OSU) and the Laboratory of Aquaculture, under a Memorandum of Understanding between the two educational institutions.

The work conducted has already had a significant impact on both theory and practice of aquaculture in Tabasco. The involvement of professors, technicians, students, and producers in the use of safe handling practices for the masculinization of Nile tilapia fry with synthetic steroids has brought a fresh perspective to aquaculture producers. Mexico as a whole just recently started using single-sex populations of tilapia. Despite the use of tilapias in extensive and semi-intensive culture systems for more than two decades in Tabasco, the practice of sex inversion started only one year ago. Probably the most important impact of the PD/A CRSP has been in the training of undergraduate students from both the aqua-culture and biology programs at UJAT.

The studies being conducted at UJAT under the CRSP project are focused on reproductive control research and environmental impacts. One series of experiments is evaluating the fate of 17a-methyltestosterone (MT) in sex inversion ponds, and people are trained on the safe handling of MT-impregnated food. Another series of experiments is investigating the potential of using short-term immersions in synthetic steroids to masculinize Nile tilapia at the farm level. If successful, this approach can minimize the risks of unintended exposure of hatchery workers as well as fish or other non-target organisms.

A major interest in the Laboratory of Aquaculture is the development and transfer of technology for the culture of native species. This issue was brought up during the 2000 CRSP annual meeting in New Orleans by several CRSP researchers and may be considered in future proposals. At UJAT, we have studied the requirements for the culture of the tropical gar (Atractosteus tropicus) for more than 10 years, and currently we are in the process of evaluating the transfer of this technology to a small-scale farm located in a rural area of Tabasco. With the participation of producers from the community of Rio Playa, municipality of Comalcalco, researchers, technicians, students, and farmers are implementing the first topical gar farm in Mexico. This effort aims to produce gar fry for restoration and enhancement of the surrounding lagoons and rivers, grow-out for food and craft production, and juvenile production for ornamental purposes. The first products of this endeavor are just coming out. Juvenile samples have been sent to Japan for ornamental purposes, and more than 10,000 juveniles were released in the surrounding habitats for stock enhancement. Finally, 5,000 juvenile gars are being cultured in grow-out earthen ponds to evaluate food production.

Aquaculture Resources and Potential in Mexico The State of Tabasco, with a population of 1.5 million habitants, is located in the southeastern region of Mexico and spans a territory of 25,267 square kilometers. The climate in Tabasco is humid tropical with intense rain during most of the year and a dry season that lasts from April to June. Tabasco has the most important hydrological basin of the country, composed by the rivers Usumacinta, Grijalba, Tonalá, and Mezcalapa, and contains about 30% of the hydrological resources of the entire country. This basin provides a substantial food resource for the local population and a significant amount of food for Mexico City’s fish market. Inherited from the Olmec ancestors, fish consumption constitutes a lifestyle in Tabasco, and many restaurants are praised by national and international tourists because of the quality and variety of their traditional seafood plates. At the national level, Tabasco is considered among the States of Mexico with the highest potential for both intensive and extensive aquacultural development. The combination of weather, water availability, and soil quality has attracted the attention of national and international investors, and many new aquaculture projects have been proposed recently. Species identified for aquaculture development include the native cichlids (genera Petenia and Cichlasoma); snooks (Centropomus); gars (Atractosteus); the introduced tilapias (Oreochromis); and several species of crabs, prawns, and mollusks.

Fisherman from Ejido Rio Playa, Tabasco, with the catch of the day--tropical gars.

Laboratory of Aquaculture Staff

Professors ~
Gabriel Márquez Couturier
Wilfrido Miguel Contreras Sánchez
Salomón Páramo Delgadillo

Technicians ~
Alejandro Mcdonal Vera
Laura Escobar Casillas
Heleodoro Reyes Reyes

Projects Underway in the UJAT Lab

• Productive projects for the sustainable use of biological richness of the Ejido Rio Playa, Comalcalco, Tabasco.
• Masculinization of Nile tilapia fry using the synthetic steroid trenbolone acetate and fate of the masculinizing agent 17a-methyltestosterone in the pond environment.
• Sustainable management of wetlands: strategies for biodiversity conservation by campesinos of the Ejido Rio Playa, Comalcalco, Tabasco.
• Population study and sustainable management strategies for the tropical gar Atractosteus tropicus in the Biosphere Reserve Pantanos de Centla.