Progress 07/01/02 to 06/30/07
Outputs
OUTPUTS: This being a project aimed at genetic improvement of aquaculture stocks, its key outputs were genetically improved lines: (1) hybrid tilapia selected for rapid growth and white body coloration, and (2) striped bass domesticated and selected for growth. These lines were developed with the active collaboration of private aquaculture operations, and were disseminated directly to them. The tilapia line currently is in production - 4 million pounds (1,814,369 kg.) per year - at Blue Ridge Aquaculture (Martinsville, VA). The striped bass line and hybrids derived from it were in production at Fins Technology (Turners Falls, MA) until its sale. The lines then were transferred to North Carolina State University, where they are subject to continuing breeding.
PARTICIPANTS: Collaborators: Bill Martin and Darrin Prillaman, Blue Ridge Aquaculture, Martinsville, VA. Scott Lindell, Brian Delbos, R. Perham, and Josh Goldman, then of Fins Technology, 15 Industrial Road, Turners Falls, MA. Training opportunity: Travis Brenden, then a doctoral candidate at Virginia Polytechnic Institute and State University, contributed statistical analyses to teh striped bass breeding study, thereby gaining training.
TARGET AUDIENCES: Target audiences: Private-sector aquaculture firms: Blue Ridge Aquaculture, Fins Technology, and striped bass production sector more generally, as regards production of stocks. Commerical aquaculture operations more generally, as regards utility of producing genetically improved stocks Research sector: Publications regarding inheritance of key aquaculture traits will improve the basis for pursuing genetic improvement of aquaculture stocks.
Impacts
To achieve genetic improvement of the tilapia, stock, I maintained a program of classical selective breeding. That is, at about one year of age, the stock was sorted on the basis of sex, and the largest, whitest broodstock candidates were selected. Eight generations of selection show continued improvement of growth rate as well as correlated changes in body conformation and docility. Other possible breeding approaches also were evaluated. Evaluation of a commercially available all-male stock showed no production gains in the systems at issue, and so we dropped the goal of developing our own all-male stock. As productivity gains still are being realized, we have elected to defer evaluation of resource strains and production of a crossbred stock. The genetic improvement of the select stock of tilapia contributed to the viability of a major commercial producer, whose production has roughly doubled since this project was initiated. This commercial success has contributed
to employment and economic growth in a depressed rural area. We evaluated the production of selected striped bass, showing that the top one-third of families reared in replicated tanks showed greater survival, growth, and feed conversion efficiency than hybrid striped bass. Hybrid striped bass produced from selected striped and selected white bass outperformed hybrids from unimproved resource stocks. After sixty days or production, hybrid striped bass exhibited significantly higher survival, growth, and feed conversion efficiency than backcross hybrid striped bass, although the backcross may have better market acceptance because of it resemblance to striped bass. Development of domesticated, select, and hybrid striped bass contributed to the commercial viability of Fins Technology. With the sale of the operation and its dedication to production of other species, the striped bass lines were transferred to an academic breeding and genetic improvement program, with the potential to
benefit the entire striped and hybrid bass production sector.
Publications
- Korol, A., A. Shirak, E. Hallerman, and A. Cnaani. 2007. Detection and analysis of QTLs for economic traits in aquatic species. Pages 169-197 in Z.J. Liu, ed. Aquaculture Genome Technologies. Blackwell Publishing, Ames, Iowa.
- Cnaani, A., E.M. Hallerman, M. Ron, J.I. Weller, Y. Kashi, G.A.E. Gall, and G. Hulata. 2003. A chromosomal region with quantitative trait loci affecting cold tolerance and fish size in an F2 tilapia hybrid. Aquaculture 223:117-128.
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Progress 10/01/05 to 09/30/06
Outputs
Development of molecular genetic markers provides aquaculture with tools for a number of research and practical applications. A combination of microsatellite DNA markers that can be screened in one multiplex assay has been developed to infer parentage in mixed-progeny groups of rainbow trout Oncorhynchus mykiss. Gene expression profiling using DNA microarrays can identify genes affecting traits of interest, providing candidates for QTL or functional analysis. Nile tilapia Oreochromis niloticus were fed one of four diets (high or low protein, high or low lipid) for nine weeks. RNA isolated from the anterior intestine was hybridized to a zebrafish microarray. Comparison of gene expression among fish fed the respective diets revealed at least two-fold expression differences for genes involved in nucleic acid binding, chromatin structure, RNA processing, ubiquitination, moiety transfer, growth factors, signaling molecules, and transport factors, among others. The results
indicate the utility of the zebrafish array for characterizing gene expression in tilapia.
Impacts
Use of the microsatellite multiplex will support cost-effective screening of mixed-progeny groups of rainbow trout, allowing (1) selection of the best broodstock candidates from each family and (2) design of matings among unrelated individuals, so as to avoid inbreeding. Improved understanding of the effects of diet on gene expression will improve understanding of fish nutrition, eventually allowing purposeful design of improved diets for tilapia.
Publications
- Hallerman, E.M. 2006. Use of molecular tools for research and improvement of aquaculture stocks. The Israeli Journal of Aquaculture. Bamidgeh 58:286-300.
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Progress 10/01/04 to 09/30/05
Outputs
In collaboration with colleagues Steve Craig, Ewen McLean, and Johanna Craig, Nile tilapia Oreochromis niloticus derived from the same genetic stock were randomly distributed into 10 1-m3 fiberglass tanks in a recirculating system. Fish (n = 20/tank) were fed one of 4 diets (50/8 [high protein], 28/8 [low protein], 32/18 [high lipid], 32/4.5 [low lipid] by hand at 3 percent body wt/day for 9 wk. At trial termination, RNA was isolated from an anterior section of intestine and hybridized to an Affymetrix zebrafish gene microarray. A clustering algorithm was employed to analyze similarity of gene expression among samples representing the respective treatments. Comparison of gene expression among fish fed the high and low protein diets revealed that the high protein diet evoked at least two-fold expression differences for genes involved in nucleic acid binding, chromatin structure, RNA processing, ubiqutination and moiety transfer. Tilapia fed the high lipid diet
exhibited elevated expression of genes encoding GABA receptors, growth factors, signaling molecules and apoptosis regulator, heat shock protein hsp70, DNA binding proteins, transport factors, helicases, cytochrome oxidases and ubiquitinases.
Impacts
Better understanding of key metabolic pathways will contribute to advances in diet formulation and may support marker-assisted selection of tilapia stocks better suited to culture conditions and feeds. In the context of genomics, results illustrate the utility of the zebrafish microarray for characterizing gene expression in tilapia. Results also highlight the potential of tilapia as an economically important teleost model of gene regulation during dietary manipulations.
Publications
- No publications reported this period
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Progress 10/01/03 to 09/30/04
Outputs
We developed a pilot-scale wastewater treatment system to treat and reuse effluent presently discharged from Blue Ridge Aquaculture (Martinsville, VA), a large-scale producer of tilapia in recirculating aquaculture systems. An initial study determined optimum ozone dosage and reaction time, ozone transfer efficiency, ozone yield coefficient, degree of pollutant removal, and other ozone and water quality parameters. The feasibility limit for ozone contact time was approximately 9 minutes at an applied ozone concentration of 23g/m3. Next, we evaluated a pilot station treatment train including sedimentation, microscreen filtration, fluidized bed denitrification, ozonation, aerobic biological oxidation in a trickling filter, and jar-test chemical flocculation. Significant improvements were found regarding solids, COD, cBOD5, NO3--N, TKN, and turbidity. Removal of foam after ozonation improved ozonation efficacy and pollutant removal. A nitrogen budget for the BRA facility
indicated that 35 percent of the nitrogen applied in feed was assimilated in fish. We evaluated the possible impact of returning treated effluent to production systems. We found that less than 1 percent of the TAN produced would return the recovered stream, and that existing biofilters can remove it.
Impacts
Sustainable tilapia production in recirculating aquaculture systems often is constrained by availability of high quality replacement water. The pilot station design that we evaluated was effective for removing organics and nutrients and can serve as the basis for scale-up for treating and reusing the entire BRA effluent stream. More importantly, the design is of general interest to the recirculating sector of the U.S. aquaculture industry.
Publications
- Halachmi, I., Y. Simon, R. Guetta, and E.M. Hallerman. 2005. A novel computer simulation model for design and management of recirculating aquaculture systems. Aquacultural Engineering, in press.
- Lindell, S.R., B. Delbos, R. Perham, J. Goldman, E.M. Hallerman, and T.O. Brenden. 2004. Hatchery and grow-out performance of sunshine bass and backcross hybrid striped bass in recirculating aquaculture systems. International Journal of Recirculating Aquaculture 5:43-54.
- Sandu, S.I. 2004. Evaluation of ozone treatment, pilot-scale wastewater treatment plant, and nitrogen budget for Blue Ridge Aquaculture. Ph.D. Dissertation, Virginia Polytechnic Institute and State University.
- Sandu, S.I., E.M. Hallerman, and N. Love. 2004. Efficacy of a pilot-scale wastewater treatment plant for a commercial aquaculture operation. Pages 1-11 in T.T. Rakestraw, L.S. Douglas, and G.J. Flick, eds. Proceedings of the Fifth International Conference on Recirculating Aquaculture. Roanoke, VA, July 22-25, 2004.
- Delabbio, J., B.R. Murphy, G.R. Johnson, and E. Hallerman. 2004. What factors influence the use of biosecurity in aquaculture? Pages 446-455 in T.T. Rakestraw, L.S. Douglas, and G.J. Flick, eds. Proceedings of the Fifth international Conference on Recirculating Aquaculture. Roanoke, VA, July 22-25, 2004
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Progress 10/01/02 to 09/30/03
Outputs
Product quality is an important aspect of product differentiation and valuation in the marketplace. Many aquaculture products are perceived by the consumer as overly fatty, and tend to spoil more rapidly than less fatty products. We are establishing the basis for improving the quality of tilapia products by quantifying the effects of different feeding practices and genetic strain on fat deposition in muscle. We are developing a method for observing fat in sections of fish by staining with lipophilic dyes and quantifying stained cross-sectional area by digital image analysis.
Impacts
Reducing fat in tilapia fillets will improve consumer acceptance and extend the period of freshness. Development of a method for observing the amount and distribution of fat in tilapia muscle will provide a precise method for quantifying the effects of husbandry conditions and genetics on that aspect of product quality. Demonstration of the method will be followed by feeding trials comparing lipid deposition in fast- and slow-growing strains with different diets or feeding regimes. Results will help the U.S. tilapia industry produce high-quality fillets that will compete well with low-cost imported products.
Publications
- No publications reported this period
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Progress 10/01/01 to 09/30/02
Outputs
Efficiency and profitability of tilapia production is enhanced by production of all-male stocks. We compared production of a genetically-male tilapia (GMT) stock with that of a population we had selectively bred for four generations. Although selectively bred males were larger, production of the GMT stock was greater because more of the stock was male. The GMT stock was only 60 percent male, likely because GMT technology was applied to an interspecific hybrid stock. Our findings show that GMT stocks would be more productive if the technology were applied to a selectively bred base stock. Many hybrid striped bass producers have expressed interest in a backcross of an F1 hybrid to striped bass. We compared growth of F1 reciprocal and backcross hybrids, and found that size-at-age of F1 hybrids exceeded that of backcross hybrids by about half.
Impacts
The Louisiana-based domestic producer and Wales-based developer of GMT technology changed their breeding practices and improved their quality control as a result of this research.
Publications
- Kidd, M., and E. Hallerman. 2002. Growth performance of genetically male and selectively bred tilapia in recirculating aquaculture systems. Fourth International Conference on Recirculating Aquaculture, July 18-21, 2002.
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