ARCHIVAL WEBSITE
You are viewing the archived website of Pond Dynamics / Aquaculture CRSP. When using this website, please understand that links may be broken and content may be out of date. You can view more information on the continuation of PD/A CRSP research archived at AquaFish Innovation Lab.
Mexico Project
PD/A CRSP Nineteenth Annual Administrative Report

Previous Section Table of Contents Next Section

Research Projects
Mexico Project

MOU No. RD009C

Staff
Oregon State University, Corvallis, Oregon

Carl B. Schreck US Principal Investigator, US Regional Coordinator
Wilfrido M. Contreras-SánchezGraduate Research Assistant (Mexico; through January 2001; CRSP funded)
Carisska AnthonyUndergraduate Student (through January 2001)
Janine GonzalezUndergraduate Student (through January 2001)
Damien Wycoff Undergraduate Student (through January 2001)


Universidad Juárez Autónoma de Tabasco, Villahermosa, Mexico

Wilfrido M. Contreras-Sánchez Host Country Principal Investigator
Gabriel Márquez CouturierHost Country Principal Investigator
Alfredo Ramos MonteroTechnician (from February 2001)
Heleodoro Reyes Reyes Technician (from January 2001)
Alejandro MacDonald VeraTechnician Student (through June 2001; CRSP funded)
Guadalupe Morales Lara Technician Student (partially CRSP funded)
Maria de Jesús Contreras GarciaUndergraduate Student (from January 2001)
Luis Arturo Dorantes Lopez Undergraduate Student
Thelma R. González Márquez Undergraduate Student
Albaro Hernández Hernández Undergraduate Student (from January 2001)
Sofia Carolina Santiago Ruiz Undergraduate Student

Cooperator
Oregon State University, Corvallis, Oregon

Martin Fitzpatrick

Site Background

The PD/A CRSP has been active in Mexico since 1997. A Memorandum of Understanding (MOU) was signed between Oregon State University (OSU) and the Universidad Juárez Autónoma de Tabasco (UJAT) in June 1999. Until 2000, research conducted in Mexico was reported as either Reproduction Control Research or Effluents and Pollution Research. Beginning with last year's report, because of exclusive collaboration between OSU and UJAT, research conducted under the differing research themes was consolidated to form the Mexico Project. CRSP research in Mexico emphasizes reproduction control through the use of hormone immersion and examines the fate of masculinizing agents in effluents.

Work Plan Research

The following Ninth Work Plan investigation continued into the current reporting period:

This MOU was also awarded funding to conduct the following Ninth Work Plan investigations:

Note: The schedule for 9RCR5C was modified. The revised schedule appears in the Addendum to the Ninth Work Plan. 9RCR5D and 9ER2D were approved after the publication of the Addendum to the Ninth Work Plan. The work plans for these investigations will appear in the Second Addendum to the Ninth Work Plan.

Networking

Contreras-Sánchez met with Oceanol representative Silvia Wizar, director of development for the municipality of Centro, Tabasco, to initiate talks regarding collaboration between UJAT and the municipality on a proposal for the production of sex-reversed tilapia using clean technologies.

Formal collaboration between UJAT and the University of San Carlos, Guatemala, will take place in the form of a project that involves the use of activated charcoal filters for the elimination of MT from intensive fry production systems. UJAT also initiated contacts with the Office for Development in the municipality of Centro, which may participate in experiments with UJAT related to the study.

Allyse Ferrara (Clemson University), Reynaldo Patiño, and Kevin Pope (both of Texas Tech University) contacted the CRSP researchers to plan a visit to UJAT to develop collaborative agreements to work with the native gar Atractosteus tropicus. Since the alligator gar has been listed as a species
at risk in Texas, both Patiño and Pope are interested in understanding how gar spawning and larval rearing are performed at UJAT.

The laboratory of aquaculture at UJAT will provide 3,000 control fish (50% males) and 3,000 masculinized fish (95% males) to a group of tilapia producers from the Sánchez Magallanes, Cardenas. The farmers will conduct a short experiment in hapas where they will grow the fish and compare growth rates.

Márquez Couturier met with a producer at the Ejido Rio Playa, Comalcalco, Tabasco, which has recently built facilities for aquacultural purposes. UJAT will provide sex-reversed tilapia and training for initiating tilapia aquaculture.

Contreras was contacted by the nongovernmental organization Santo Tomás, a group that is interested in writing a proposal to work in collaboration with UJAT for developing the culture in hapas of masculinized mojarra castarrica (Cichlasoma urophthalmus), a native cichlid.

A group of producers from Huimanguillo requested information regarding the use of masculinized tilapia fry. UJAT will provide fry to start small production systems depending upon the producers' ability to form effective working groups.

The researchers received a request from Aqua Technics of Carlsborg, Washington, to analyze fish food for methyltestosterone, and the assays were conducted.

Educational Outreach

The UJAT laboratory is currently involved in training workshops for tilapia culture organized by Fideicomisos Instituidos en Relación con la Agricultura (FIRA). Candelario Bautista, a volunteer at UJATs laboratory, has already participated in two workshops, one of which was conducted in Sánchez Magallanes. The researchers are emphasizing the use of masculinized tilapia, and the laboratory is providing information for the workshop.

Publication

Contreras-Sánchez, W., 2001. Sex determination in Nile tilapia, Oreochromis niloticus: Gene expression, masculinization methods, and environmental effects. Ph.D. dissertation, Oregon State University, Corvallis, Oregon.

Conference

PD/A CRSP Annual Meeting at Orlando, Florida, 26 January 2001. (Contreras-Sánchez)

Award

Schreck received the Excellence in Fisheries Education Award from the American Fisheries Society.

Masculinization of Tilapia by Immersion in Trenbolone Acetate: Detection of Trenbolone Acetate in Water after Treatment

Ninth Work Plan, Reproduction Control Research 5C (9RCR5C)
Final Report

Wilfrido M. Contreras-Sánchez
Laboratorio de Acuacultura
Universidad Juárez Autónoma de Tabasco
Villahermosa, Tabasco, Mexico

Martin S. Fitzpatrick
Department of Fisheries and Wildlife
Oregon State University
Corvallis, Oregon, USA

Carl B. Schreck
Oregon Cooperative Fishery Research Unit
Biological Resources Division—US Geological Survey
Department of Fisheries and Wildlife
Oregon State University
Corvallis, Oregon, USA

Abstract

In a previous experiment in which Nile tilapia fry were successfully masculinized, we investigated how the concentration of trenbolone acetate (TA) in the immersion water changed before and after treatment. The results from that experiment indicated that the concentration of TA before and after treatment of Nile tilapia fry was highly variable and below the expected levels. Therefore, we decided to corroborate those results by running two experiments in which fry were not present and by testing different water sources. These new experiments confirmed our previous findings, indicating that independently of the source of water, the concentration of TA is highly variable and below the expected levels.

Masculinization of Nile Tilapia Fry by Immersion in Trenbolone Acetate: Reuse of Hormone Solution and Effects of Temperature

Ninth Work Plan, Reproduction Control Research 5D (9RCR5D)
Final Report

Wilfrido M. Contreras-Sánchez, Gabriel Márquez-Couturier, Thelma Ruth González Márquez, and Luis Arturo Dorantes Lopez
Laboratorio de Acuacultura
Universidad Juárez Autónoma de Tabasco
Villahermosa, Tabasco, Mexico

Carl B. Schreck
Oregon Cooperative Fishery Research Unit
Biological Resources DivisionUS Geological Survey
Department of Fisheries and Wildlife
Oregon State University
Corvallis, Oregon, USA

Abstract

Preliminary studies in our laboratory showed that short immersions in the synthetic androgen trenbolone acetate (TA) constitute a good option for masculinizing Nile tilapia fry produced by a single female. This technique offers the potential to replace MT feeding for 28 days and avoid steroid accumulation in pond sediments. We investigated the effects of TA treatment on fry collected from a tank containing batches produced in multiple spawnings. Our results suggest that masculinization involving short-term immersions in TA results in significantly more males in the treated groups (55.9 and 61.6%) than in the controls (44.5 and 38.9%). However, the percentage of males produced is far below that recommended for aquacultural purposes. We further investigated the potential enhancing effects of elevated temperatures in combination with TA treatment during immersion time and found no significant effects of temperature on the proportion of males obtained.

Fate of Methyltestosterone in the Pond Environment: Use of MT in Earthen Ponds with No Record of Hormone Usage

Ninth Work Plan, Effluents and Pollution Research 2D (9ER2D)
Final Report

Wilfrido M. Contreras-Sánchez and
Gabriel Márquez Couturier
Laboratorio de Acuacultura
Universidad Juárez Autónoma de Tabasco
Villahermosa, Tabasco, Mexico

Carl B. Schreck
Oregon Cooperative Fishery Research Unit
Biological Resources DivisionUS Geological Survey
Department of Fisheries and Wildlife
Oregon State University
Corvallis, Oregon, USA

Abstract

The following study examined the persistence of 17a-methyltestosterone (MT) in the environment after its use for masculinizing Nile tilapia in nursery ponds located in the Universidad Juárez Autónoma de Tabasco, Mexico. Fry harvested from spawning ponds were treated with a masculinizing dose of MT (60 mg kg-1) for four weeks. Concentrations of MT were determined by radioimmunoassay. MT was not detectable in the water at any time. In the sediments, MT was not detectable during the first 10 days of treatment. Afterwards MT was detectable in all sampling points (mean = 146.7 pg g-1; SE = 21.3). MT values varied from not detectable to 368.9 pg g-1. Masculinizing efficiency was low in the first trial (87.4% males) but increased significantly afterwards, reaching 92.6% males in the second trial and 98.7% in the third trial.

Another outcome of this investigation is a manual on tilapia masculinization using synthetic steroids. This manual is intended to reach fry producers, extension agents and technicians; it contains a general description of the biology of the tilapias, traditional culture practices, masculinization methods, and a detailed section on safe handling of steroids.


Previous Section Table of Contents Next Section