Aquaculture CRSP
PD/A CRSP
Management Entity Oregon State University 418 Snell, Corvallis OR 97331
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PD/A CRSP Twentieth Annual Administrative Report

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Research Projects
Mexico Project

Subcontract No. RD009C

Staff

Oregon State University, Corvallis, Oregon
Carl B. Schreck US Principal Investigator
Guillermo R. Giannico US Principal Investigator

Universidad Juárez Autónoma de Tabasco, Villahermosa, Mexico
Wilfrido M. Contreras-Sánchez Host Country Principal Investigator
Gabriel Márquez Couturier Host Country Principal Investigator
Mario Fernández Perez Host Country Principal Investigator
Alfredo Ramos Montero Technician
Guadalupe Morales Lara Technician Student (Mexico; partially CRSP funded)
Bernardita Campos Campos Graduate Student (Mexico; partially CRSP funded from January 2002)
Candelario Bautista Cruz Graduate Student (Mexico; September 2001)
Alejandro McDonal Vera Graduate Student (Mexico)
Ulises Hernández Vidal Graduate Student (Mexico; partially CRSP funded)
María Fernanda Cifuentes Alonso Undergraduate Student (Mexico; partially CRSP funded from September 2001)
Gisela Filigrana Celorio Undergraduate Student (Mexico; partially CRSP funded from September 2001)
Maria de Jesús Contreras Garcia Undergraduate Student (Mexico; partially CRSP funded)
Gabriel Real Ehuan Undergraduate Student (Mexico; partially CRSP funded)
Caleb Ramirez Feria Undergraduate Student (Mexico; volunteer from July 2002)
Rafael Martinez Garcia Undergraduate Student (Mexico; volunteer from July 2002)
Gabriel Hernández Hernández Undergraduate Student (Mexico; partially CRSP funded)
Gabriela Arias Jiménez Undergraduate Student (Mexico; volunteer from July 2002)
Guadalupe Morales Lara Undergraduate Student (Mexico)
Emil Paolo Ramon López. Undergraduate Student (Mexico; from December 2001)
Juan Manuel Vidal López Undergraduate Student (Mexico; volunteer from July 2002)
Luis Arturo Dorantes López Undergraduate Student (Mexico; partially CRSP funded)
Mariela Frias López Undergraduate Student (Mexico; partially CRSP funded)
Abigael Chávez Méndez Undergraduate Student (Mexico; partially CRSP funded from September 2001)
Isidro López Ramos Undergraduate Student (Mexico; partially CRSP funded from September 2001)
Milciades De la Cruz Rodríguez Undergraduate Student (Mexico; from September 2001)
Rocío Chan Rodrígues Undergraduate Student (Mexico; partially CRSP funded from April 2002)
Daniel Alejandro López Sanlucar Undergraduate Student (Mexico; volunteer from July 2002)
Sergio Gómez Triano Undergraduate Student (Mexico; partially CRSP funded from September 2001)
Luis Emanuel Pascual Valencia Undergraduate Student (Mexico; volunteer from July 2002)

Work Plan Research

This subcontract was awarded funding to conduct the following Tenth Work Plan investigations:

Note: In addition to the above investigations, Universidad Juárez Autónoma de Tabasco also collaborates with University of Arizona (10NSR3C and 10NSR3D), Ohio State University (10RCR1), and University of Arkansas at Pine Bluff (10MEAR2A). The schedule for 10ER2 was modified. The revised schedule appears in the forthcoming Addendum to the Tenth Work Plan.

Publications

Bart, A., W.M. Contreras-Sánchez, and M. Fitzpatrick. Ultrasound enhanced masculinization of Nile tilapia, Oreochromis niloticus, in immersion protocol. J. World Aquacult. Soc. (in review)

Contreras-Sánchez, W.M. Identification of unique genes expressed during sex inversion of Nile tilapia, Oreochromis niloticus by cDNA subtractive hybridization. Gen. Comp. Endocrinol. (in review)

Lara, G.M., 2001. Ictiofauna Asociada a las Escolleras del Puerto Marítimo de Dos Bocas, Paraíso, Tabasco, México. División Académica de Ciencias Biológicas, B.S. thesis, Universidad Juárez Autónoma de Tabasco.

Elimination of Methyltestosterone (MT) from Intensive Masculinization Systems: Use of Activated Charcoal in Concrete Tanks

Tenth Work Plan, Effluents and Pollution Research 2 (10ER2)
Abstract

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

Guillermo R. Giannico
Department of Fisheries and Wildlife
Oregon State University
Corvallis, Oregon, USA

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

Abstract

This study tested the hypothesis that activated charcoal eliminates 17a-methyltestosterone (MT) from the water used in intensive sex-inversion systems. Two charcoal amounts (2.5 and 5.0 kg) placed in filters and a control group (no charcoal) were evaluated for both sex-inversion efficacy and MT persistence in water. Fry (2,200 to 2,945 fry m-3) were kept in concrete ponds with 7.13 m3 of water and were fed a masculinizing dose of MT (60 mg kg-1) during their first four weeks. Water samples were collected from the sex-inversion tank before the treatment and on a weekly basis starting with the first day of treatment. The activated charcoal used in this experiment was exposed to direct sunlight for 24 and 48 h, and samples were collected at different times for MT detection. All samples will be extracted using ether, and the concentration of MT will be determined by radioimmunoassay at Oregon State University. Masculinization rates were not significantly different (P > 0.05) between treatments in a trial or between trials. Mean percentage of males for treatments with 0.0, 2.5, and 5.0 kg of activated charcoal were 92.0, 94.3, and 92.7%, respectively. Control groups averaged 51.7% males and had significantly fewer males than the MT-fed groups (P < 0.0001). Once the concentration of MT in the water is known, we will be able to recommend a system that efficiently masculinizes tilapia without producing steroid-contaminated effluents.

Diversification of Aquacultural Practices by Incorporation of Native Species and Implementation of Alternative Sex Inversion Techniques

Tenth Work Plan, Appropriate Technology Research 3 (10ATR3)
Abstract

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

Guillermo R. Giannico
Department of Fisheries and Wildlife
Oregon State University
Corvallis, Oregon, USA

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

Abstract

This project aims to determine if administration of steroids via bioencapsulation is an efficient method for sex inversion of carnivorous species of fish in aquaculture. This technique offers the advantage that the larvae of such species strongly prefer live food over artificial diets. To determine accumulation of estradiol (E2) and trenbolone acetate (TA) in Artemia (brineshrimp), we immersed nauplii in solutions containing 1,000 mg l-1 of steroid. The steroid was dissolved in ethanol to a concentration of 1 mg ml-1 and then added to the water. Controls were immersed in water containing only the ethanol vehicle. Each treatment consisted of three replicates. Water samples (50 ml) from glass jars containing Artemia spp. nauplii were collected at 0, 2, 4, 6, 12, 16, 20, and 24 h. Nauplii were washed in nanopure water and dried, and samples were frozen (–20°C) and preserved until processing. All samples were extracted using ether, and the concentration of steroid was determined by radioimmunoassay for E2 or high performance liquid chromatography for TA. Immediately after addition of the steroid, nauplii had E2 concentrations greater than 1,500 pg g-1 and TA concentrations greater than 2,000 pg g-1. The nauplii treated with E2 had 5,500 pg g-1 at 2 h, remained at that level until 6 h, and then accumulated more estrogen to reach a concentration of 7,000 pg g-1 at 12 h; this concentration remained until 24 h. A similar pattern was observed when TA was used; however, at 24 h, concentrations declined to 5,000 pg g-1. Controls showed background levels. Our results indicate that Artemia spp. readily accumulates steroids and can be used for sex-inversion purposes. We are currently evaluating the efficacy of bioencapsulated steroids for sex inversion.

Selection of a New Nile Tilapia Genetic Line to Provide Broodstock for Southeastern Mexico

Tenth Work Plan, Reproduction Control Research 2 (10RCR2)
Abstract

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

Guillermo R. Giannico
Department of Fisheries and Wildlife
Oregon State University
Corvallis, Oregon, USA

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

Mario Fernández-Perez
División Académica de Ciencias Agropecuarias
Universidad Juárez Autónoma de Tabasco
Villahermosa, Tabasco, Mexico

Abstract

Because of its geographic and hydrological components, the southeastern region of Mexico has been considered one of the top areas in Mexico for aquaculture and especially for tilapia culture. However, good quality fry is not available, and this problem affects farmers interested in culturing tilapia. We have initiated a selective breeding program using 220 females and 110 males selected from a batch of fish purchased from Egypt by the Tabasco State government. This first batch was selected using a discriminant analysis for fish that best resembled Nile tilapia (Oreochromis niloticus). The analysis was based on length, weight, number of scales, fins, head length, mouth diameter and eye diameter. These fish were stocked in 200 m2 ponds for grow-out. From the fry obtained from breeding of these fish, three selections were made: 1) at day 60 post-harvest; 2) at 120 d (at this point the fish were separated by sex); and 3) at 11 months post-harvest. A total of six hundred females and 400 males were selected based on a combination of best length and condition factor of the F1 generation. These fish were stocked in 200 m2 ponds and allowed to breed. From the fry obtained from this second breeding, 60% of the total were selected for grow-out. After four months, two lines were separated based on 50% of the fish stocked—one based on length and one based on a combination of best length and condition factor. We are currently growing these fish, and the final selection will be conducted in September 2002. We were able to combine the efforts of two projects, one supported by the Consejo Nacional de Ciencia y Tecnología (CONACYT) and the other one by the PD/A CRSP. This combined effort has allowed us to work at the Mariano Matamoros Hatchery using 200, 1,000, and 2,000 m2 ponds and to use fish originally selected by Mario Fernández-Perez in 2000.


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The Pond Dynamics/Aquaculture CRSP is funded under USAID Grant No. LAG-G-00-96-90015-00 and by the participating US and Host Country institutions. Questions for or about the PD/A CRSP? Comments about this site? Email ACRSP@oregonstate.edu.

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