Progress 10/01/01 to 09/30/07
Outputs
OUTPUTS: The project evaluated the potential for survival of tilapia in sub-optimal temperatures and elevated salinities. Genetic effects influencing salinity and cold tolerance were also evaluated. Information pertaining to the potential for acclimation and survival of juvenile tilapia under prevailing temperatures and salinities in Louisiana's coastal waters was relayed to marine extension agents, natural resource managers and policy makers within the state, as well as at various scientific meetings. A total of three master's theses and numerous presentations at professional meetings resulted from this work. The project also examined methodologies for producing polyploid tilapia, resulting in the development of novel incubation and heat-shock approaches. One master's thesis was published. Results were disseminated to the scientific community through conference presentations and directly to industry and resource managers. Another component of the project established the utility of
polyculture of juvenile freshwater drum to control snail-harboring parasites in catfish fingerling production. An additional, on-going component seeks to develop baseline information and methods for reliable production of juvenile freshwater drum, with limited captive spawning occurring for the past three years. Results from these trials have been presented at one scientific meeting, at catfish producer and commodity group meetings, and in news releases.
PARTICIPANTS: Graduate students who participated in these activities include Eric Herbst, Patricio Paz, Robert Nugon and Alvaro Armas. Numerous undergraduate student workers participated and acquired valuable scientific training. Collaborators included the Louisiana Catfish Promotion and Research Board, professionals at Louisiana Department of Wildlife and Fisheries, as well as Dr. Conrad Kleinholz at Langston University in Oklahoma. Contacts included various academic, government and commercial interests in the U.S. and Latin America.
TARGET AUDIENCES: Target audiences for tilapia research included the scientific community, tilapia producers, and resource managers in the Gulf region and in other countries throughout the Americas. These audiences were reached through direct contacts, presentations at meetings and workshops in the U.S., Mexico and Honduras, and journal articles are in preparation. Target audiences for drum research included catfish producers and academics in the mid-south and mid-west U.S. These audiences were primarily reached through direct contact and presentations at meetings. Graduate and undergraduate students benefitted from practicum experiences and experiential learning.
Impacts
Much-needed information was generated related to the environmental tolerances of tilapia, genetic influence over those tolerances, and potential for establishment of tilapia in sub-tropical environments. Although most varieties are somewhat salinity tolerant, results suggest little or no potential for tilapia to 'adapt' to cold temperatures in coastal watersheds along the northern Gulf of Mexico. Estimates of direct heterosis, cross heterosis, maternal effects, line effects, reciprocal and specific reciprocal effects, and general and specific combining abilities were developed for cold and salinity tolerance. Results pertaining to genetic influences over salinity tolerance are being applied in other countries to allow tilapia culture as a sustainable alternative in marginally-profitable shrimp farming operations. Statistical models and contrasts developed for the full diallel cross analysis will allow for more robust genetic analyses with other aquatic species than
have previously been possible. Techniques developed for producing and incubating newly-ovulated tilapia eggs will foster additional work related to genetic improvement of these species. The potential of the freshwater drum as a management tool for snail control in warmwater aquaculture has been established. This, in turn, has spurred interest in developing methods to reliably produce fingerlings of this native species.
Publications
- Armas-Rosales, Alvaro M. 2006. Genetic effects influencing salinity and cold tolerance in tilapia. Master's Thesis. Louisiana State University. On-line Resource: http://etd.lsu.edu/docs/available/etd-11172006-085843/
- Lutz, C.G. 2006. Recent directions in Genetics. In Chhorn Lim and Carl D. Webster (Editors), Tilapia: Biology, Culture and Nutrition (pp. 139-180). Haworth Press, Binghamton, N.Y.
- Lutz, C.G. 2007. Genetics and Breeding: Snapper Culture. Aquaculture Magazine 33(3).
- Lutz, C.G. 2007. Genetics and Breeding: Improving Farm-Raised Shrimp. Aquaculture Magazine 33(5).
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Progress 01/01/06 to 12/31/06
Outputs
Genetic effects influencing salinity tolerance (ST) and cold tolerance (CT) were evaluated in two full diallel mating designs using six tilapia varieties (FL=Florida, BL=Blue, MO=Mozambique, RE=RedNile, MC=Mississippi, NI=Nile). Estimates of direct heterosis (hi), cross heterosis (hij), maternal effects (mi), line effects (li), reciprocal and specific reciprocal effects (rij and r**ij), and general and specific combining abilities (GCA and Sij) were developed. FL exhibited significant GCA (P < 0.01) for salinity tolerance. BL, FL, and MO exhibited highly significant li (P < 0.01). Highly significant mi (P < 0.01) was apparent for FL and RE. Highly significant Sij and hij% (P < 0.01) were exhibited in two and eight variety combinations (VCs), respectively. Highly significant rij (P < 0.01) was observed in BL-MO, and MC-RE. In addition, highly significant r**ij (P < 0.05) was noted in BL-MO and FL-RE. For CT, BL, MC and RE exhibited significant GCAs (P < 0.05). Highly
significant li and mi (P < 0.01) were apparent in BL and RE, respectively. Significantly negative Sij (P < 0.05) was exhibited only in BLxMC, while negative and significant hij% (P < 0.05) was apparent in BLxMC, FLxMO and FLxRE. Highly significant rij (P < 0.01) was apparent in FL-MC and MC-RE, while negative and significant r**ij (P < 0.05) was exhibited only in FL-MC. No significant direct heterosis (hi) was apparent in ST or CT. Improvement in ST could be accomplished by combining selection, hybridization and backcrossing in MO, BL and FL, while improvement of CT may be accomplished by selection and hybridization in BL. Results suggest little or no potential for tilapia to 'adapt' to cold temperatures in watersheds along the northern Gulf of Mexico. Captive-raised freshwater drum were maintained for spawning in the spring of 2006. A reluctance to eat both pelleted feeds and live crawfish was noted, at least for fish under 10 inches total length. These drum did not spawn in tanks
during the spring of 2006, although drum of similar age and size have been reported to spawn in research ponds in Oklahoma. Approximately 87 wild adult drum were collected between December 2005 and March 2006 through the assistance of Louisiana Department of Wildlife and Fisheries and the U.S. Fish and Wildlife Service. Drum handled and traveled well, with 92 percent survival recorded over the following two months. Drum were stocked in ponds with adult koi carp to provide fingerling koi as a forage. In spite of the loss of approximately 25 percent of these adult drum due to an unexpected oxygen depletion in one of two holding ponds, surviving fish spawned in ponds during the spring of 2006. Currently, an estimated 200 to 300 young of the year drum are being held for additional polyculture trials with catfish. Approximately 50 adult fish are being held to provide data on maturation and spawning patterns using ultrasound and catherization. Fingerlings produced from 2006 spawns were
between 6 and 8 inches by late October.
Impacts
The statistical models developed for this analysis will allow for more robust genetic analyses with other aquatic species than have previously been possible. Results will allow aquaculturists in many countries to more efficiently develop breeding programs to improve tilapia salinity and cold tolerances, and provide resource managers with additional insight as to the possibility of establishment of feral tilapia populations. The potential of the freshwater drum as a management tool for snail control in warmwater aquaculture has been established, but this potential can only be realized once techniques are developed for reliable fingerling production.
Publications
- Lutz, C.G. 2006 Egg nursery conditions. In: Aquaculture Compendium. CAB International, Wallingford, Oxfordshire, UK.
- Lutz, C.G., Armas, A. and Beverlin, L. 2006. Genetic effects influencing salinity and cold tolerance in crosses among six varieties of tilapia, Oreochromis sp. Book of Abstracts - Aquaculture America 2006 - February 13-15, 2006, Las Vegas, Nevada
- Lutz, C. Greg. 2006. The Asian catfishes, Pangasius bocourti and Pangasius hypophthalmus. Aquaculture Magazine 32(2).
- Lutz, C. Greg. 2006. Improving two or more traits through selection - a shrimp selection example. Aquaculture Magazine 32(3).
- Lutz, C. Greg. 2006. Genetic influences over disease resistance. Aquaculture Magazine 32(4).
- Lutz, C.G. 2006 Water recirculation technology. In: Aquaculture Compendium. CAB International, Wallingford, Oxfordshire, UK.
- Lutz, C.G. 2006 Stocking and harvesting strategies. In: Aquaculture Compendium. CAB International, Wallingford, Oxfordshire, UK.
- Lutz, C.G. 2006 Monoculture / polyculture. In: Aquaculture Compendium. CAB International, Wallingford, Oxfordshire, UK.
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Progress 01/01/05 to 12/31/05
Outputs
A diallel mating design was executed involving reciprocal crosses among males and females of six varieties of tilapia, including 3 pure species, two synthetic strains, and one back-crossed line. Most (28 of 36) crosses produced sufficient numbers of offspring for analysis of line, maternal and heterotic influences on environmental tolerances. Juveniles were subjected to cold and salinity tolerance step-stress trials to determine survivorship curves and preliminary survivorship curves were generated. This mating design was replicated, with higher spawning success, generating 4 additional tolerance trials for both cold and salinity. Data analysis is underway, with appropriate contrasts between survivorship to determine line effects, maternal effects, general combining abilities, and specific combining abilities. A number of captive-raised freshwater drum from two studies in 2004 were raised during 2005 for spawning in the spring of 2006. Feed habits were evaluated, with
a reluctance to eat both pelleted feed and live crawfish, at least for these fish under 25 cm total length. No preferences for physid or planorbid snails were apparent - both were completely consumed by growing drum. Additionally, 25 wild adult drum were collected in December 2005, with 92 percent survival over the following two months.
Impacts
These results will allow aquaculturists in many countries to more efficiently develop breeding programs to improve tilapia salinity and cold tolerances, and provide resource managers with additional insight as to the possibility of establishment of feral tilapia populations. The potential of the freshwater drum as a management tool for snail control in warmwater aquaculture has been established, but this potential can only be realized once techniques are developed for reliable fingerling production.
Publications
- Lutz, C. Greg. 2005. Production of Turtle Hatchlings. Pages 209-216 in: A.M. Kelly and J. Silverstein, eds. Aquaculture in the 21st Century. American Fisheries Society, Bethesda, Maryland.
- Lutz, C. Greg. 2005. Viewing Urban Aquaculture as an Agroindustry. Pages 15-24 in: B. Costa-Pierce, A. Desbonet, P. Edwards and D. Baker, eds. Urban Aquaculture. CABI Publishing, Oxfordshire, UK.
- Lutz, C. Greg. 2005. GENETICS AND BREEDING. Updates From Aquaculture America 05 In New Orleans. Aquaculture Magazine 31(1).
- Lutz, C. Greg. 2005. GENETICS AND BREEDING. Genes Change...or, Concerns Over Genetic Sustainability. Aquaculture Magazine 31(2).
- Lutz, C. Greg. 2005. GENETICS AND BREEDING. Some Recent Advances in Shrimp Genetics. Aquaculture Magazine 31(3).
- Lutz, C. Greg. 2005. GENETICS AND BREEDING. Genetically Modified Fish. Their Problems and Potential. Aquaculture Magazine 31(5).
- Lutz, C. Greg. 2005. GENETICS AND BREEDING. Genetic Improvement in the African Sharptooth Catfish: Status and Potential. Aquaculture Magazine 31(6).
- Poleo, German A., C. Greg Lutz, Gina Cheuk and Terrence R. Tiersch. 2005. Fertilization by intracytoplasmic sperm injection in Nile tilapia (Oreochromis niloticus) eggs. Aquaculture Volume 250, Issues 1-2 , 14 November 2005, Pages 82-94
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Progress 01/01/04 to 12/31/04
Outputs
Two studies were conducted to evaluate the potential for snail control in warmwater fish ponds using freshwater drum. In the first study, conducted in cool/cold water conditions from November through May, 20 outdoor tanks with approximately 15 cm of soil were filled with pond water to a depth of 0.8 m, seeded with 20 adult planorbid snails each, and supplied with aeration via airstones and compressed air. Young-of-the-year freshwater drum were stocked at two densities (approximately 2100 and approximately 4200 per ha). Two sizes at stocking (9.5 cm and 15 cm average length) were also evaluated. Four pools were used for each size/density combination, plus four control pools. At the end of May overall drum survival was approximately 84 percent. Survival did not differ significantly between size groups. Snail control also did not differ significantly between size groups. No significant differences were apparent in snail control between densities. Presence of drum, at
either density, significantly (P < 0.01) reduced snail populations. Snails per 3-m2 sample averaged 65.7, 4.4 and 4.3 for 0, 2100 and 4200 drum per hectare, respectively. The second study was conducted from June through November. Sixteen tanks were utilized with yearling drum ranging from18 to 23 cm in length. Seven tanks were stocked with 2100 drum per ha and 10,500 catfish swim-up fry (20 mm) per ha. Five tanks were stocked only with swim-up fry at the same rate, and four tanks were used as controls, with no fish. All tanks were stocked with 20 adult planorbid snails. Drum survival was 100 percent, while catfish survival was 43 percent in polyculture and 60 percent in monoculture. These differences were not significant. No snails were found in the presence of drum, while catfish monoculture and control tanks had significantly higher numbers of snails per 3-m2 sample (74 and 33, respectively). A diallel mating design was executed involving reciprocal crosses among males and females
of six varieties of tilapia, including 3 pure species, two synthetic strains, and one back-crossed line. Most (28 of 36) crosses produced sufficient numbers of offspring for analysis of line, maternal and heterotic influences on environmental tolerances. Juveniles were subjected to cold and salinity tolerance step-stress trials to determine survivorship curves. Data analysis is underway, with appropriate contrasts between survivorship to determine line effects, maternal effects, general combining abilities, and specific combining abilities.
Impacts
These results will allow Louisiana and other Gulf of Mexico states to more objectively evaluate risks associated with tilapia production in coastal watersheds by quantifying the salinity tolerances, cold tolerances, and their interaction in commercially important tilapia varieties. There is a need to evaluate the potential of the freshwater drum as a management tool for snail control and endangered mussel restoration.
Publications
- Lutz, C.G. and R.P. Romaire. 2004. Procambarid crawfish farming: low input crustacean aquaculture. Aquaculture 2004, World Aquaculture Society, 1-5 March 2004, Honolulu, Hawaii. p. 365 (Abstract)
- Engie, C., J. Avery, H. Daniels, D. Heikes, and G. Lutz. 2004. Guidelines for developing aquaculture research verification programs. SRAC Publication No. 5000, Southern Regional Aquaculture Center, National Warmwater Aquaculture Research Center, Mississippi State University, Stoneville, MS. p. 6.
- Lutz, C.G. 2004. Genetic Improvement In Striped Bass And Hybrids - Part One: Natural Variation. Aquaculture Magazine, 30(1).
- Lutz, C.G. 2004. Genetic Improvement In Striped Bass...Part Two: Cost And Benefits Of Hybridization. Aquaculture Magazine, 30(2).
- Lutz, C.G. 2004. Stock Considerations For Small Producers. Aquaculture Magazine, 30(3).
- Lutz, C.G. 2004. Genetic Improvement In Striped Bass...Part Three: Where Do We Go From Here? Aquaculture Magazine, 30(4).
- Lutz, C.G. 2004. Experiencias en el Cultivo de Peces Marinos. Memorias del VII Simposio Centroamericano de Acuacultura, Tegucigalpa 25-28 de Agosto.
- Lutz, C.G. 2004. Sistemas de Recirculacion para el Cultivo Intensivo de Peces. Memorias del VII Simposio Centroamericano de Acuacultura, Tegucigalpa 25-28 de Agosto.
- Lutz, C.G. 2004. Mejoramiento genetico de Tilapia. Memorias del VII Simposio Centroamericano de Acuacultura, Tegucigalpa 25-28 de Agosto.
- Lutz, C.G. 2004. Blue Tilapia - An Under-Valued Commercial Resource? Aquaculture Magazine, 30(5).
- Lutz, C.G. 2004. When Hybrids Attack. Aquaculture Magazine, 30(6).
- Lutz, C.G., F.S. Sanders, and R.P. Romaire. 2004. Aquaculture: aquaculture production best management practices. Publication 2894, Louisiana State University Agricultural Center, Baton Rouge, LA. 27 p.
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Progress 01/01/03 to 12/31/03
Outputs
Seven tilapia varieties were grown in fresh and brackishwater mesocosms. Nile tilapia was stocked in three freshwater pools. Every other variety was stocked into six pools, in three of which salinity was increased to 23 ppt over 14 days. In freshwater, yield of Mississippi Commercial (MCS) was higher (P< 0.05) than that of all other varieties. In brackishwater, blue tilapia yield was higher (P< 0.05) than that of all other varieties. Four tilapia varieties were subjected to three temperature reduction regimes: rapid (-0.5 C/ 5 h), moderate (-1 C/ 24 h) and gradual (-1 C/ 48 h) and to the moderate regime at three salinities (0, 5 and 10 ppt). No significant differences were observed in cold tolerance among varieties within regimes. Salt did not improve the cold tolerance of blue, Nile and MCS but slightly improved that of Florida red tilapia (FRT). The effect of temperature reduction regime on cold tolerance was significant. Juvenile (4 g) tilapia of four varieties
were tested for salinity tolerance by subjecting them to four salinity regimes during 97 h with up to 63 h acclimation. Salinity regimes represented salinities found along coastal Louisiana. Each variety was challenged individually against every other variety and thus in triplicate. Juvenile O. aureus, O. niloticus, and Florida red tilapia exhibited good survival (> 81%) in salinity regimes up to 20 ppt, with moderate survival of O. aureus (54%) and Florida red tilapia (33%) at 35 ppt salinity. Mississippi commercial tilapia survived salinity regimes up to 10 ppt and exhibited poor survival at 20 ppt (5%). The potential for acclimation and survival of juvenile tilapia in Louisiana coastal aquatic habitats was evaluated based on a comparison of trial results with prevailing seasonal salinities in coastal waters. The study indicated O. aureus, O. niloticus, and Florida red tilapia could survive salinities throughout the year along coastal Louisiana. Freshwater drum juveniles were
obtained from Dr. Conrad Kleinholz, Langston University, Langston, Oklahoma. Eight treatment combinations representing various densities of freshwater drum and snails will be evaluated in a series of 24, 2 m dia outdoor mesocosms, managed to simulate warmwater ponds. Four size/stocking density treatments for freshwater drum (including a control with no fish) will be based on preliminary results generated at Langston University during 2001 and 2002. Two initial planorbid snail density treatments will be determined based on the range of typical population levels found in commercial catfish production ponds. Drum and snails will be cultured with channel catfish fingerlings (stocked at 5000 fish per acre) for an entire growing season. Indices of snail densities will be generated by periodically deploying devices similar to commercially-available invertebrate samplers. Within each pool, all fish will be counted, measured and weighed at the end of the study and all (visible) snails will be
counted. Sub-samples of snails will be weighed and measured to determine average size and size variation.
Impacts
These results will allow Louisiana and other Gulf of Mexico states to more objectively evaluate risks associated with tilapia production in coastal watersheds by quantifying the salinity tolerances, cold tolerances, and their interaction in commercially important tilapia varieties. There is a need to evaluate the potential of the freshwater drum as a management tool for snail control and endangered mussel restoration.
Publications
- Lutz, C.G. 2003. Asian Oysters in the Chesapeake Bay. A New Beginning? Aquaculture Magazine, 29(3).
- Lutz, G., F. Sanders, and R. Romaire. 2003. Louisiana Aquaculture Production Best Management Practices (BMPs). Louisiana State University Agricultural Center, Baton Rouge, Louisiana, Publication 2894, 30 p.
- Nugon, R.W. 2003. Salinity Tolerance of Juveniles of Four Varieties of Tilapia. Master's Thesis, Louisiana State University. http://etd02.lnx390.lsu.edu/docs/available/etd-0404103-035324/
- Lutz, C.G. 2003. Genetic improvement in freshwater prawns. Aquaculture Magazine, 29(1).
- Lutz, C.G. 2003. Polyculture: Principles, Practices, Problems and Promise. Aquaculture Magazine, 29(2).
- Paz, P.E. 2003. Evaluation of Growth, Production and Cold Tolerance of Four Varieties of Tilapia. Master's Thesis, Louisiana State University. http://etd.lsu.edu/docs/available/etd-12222003-115435/
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Progress 01/01/02 to 12/31/02
Outputs
Salinity tolerance of juvenile tilapia from four commercial varieties was evaluated by subjecting them to four 97-h salinity regimes with acclimation periods of up to 63 h. Regimes represented salinities commonly found along coastal Louisiana. Juvenile Nile, blue and Florida Red (FR) tilapia exhibited > 80% survival up to 20 ppt, with limited survival at 35 ppt (0%, 54% and 33%, respectively). Results indicated these varieties could survive year-round in salinities encountered in coastal watersheds. Mississippi Commercial (MC) tilapia survived salinities up to 10 ppt, but exhibited poor survival (5%) at 20 ppt. Stocking of single-female Nile tilapia in 80-L aquaria yielded a reliable supply of eggs for polyploidy research. In one year, 72 spawns were recorded from 10 aquaria, yielding approximately 90,000 eggs. Peak spawning occurred during the summer. Two hatching systems were developed for artificial incubation of tilapia eggs, with 75% of control (untreated) eggs
surviving to hatch. Methylene blue and UV radiation reduced losses of eggs to fungal or bacterial infection. Use of glass test tubes as hatching vessels allowed for constant rolling of eggs and easy viewing and access. Use of egg baskets for rapid and uniform heat shocking of multiple treatments of Nile tilapia eggs resulted in successful induction of polyploidy. Tetraploidy and triploidy were induced by application of 3-min, 42.8 C heat shocks to eggs at 22 - 28 min post-fertilization (PF). Shocks applied at 24 min PF resulted in the highest tetraploid yield. This is the first study to report the simultaneous induction of tetraploidy and triploidy in Nile tilapia within treatments from a single spawn, raising questions regarding technical, maternal and genetic effects on synchrony of zygotic development. Clear-water recirculating systems were used to evaluate commercial performance of four varieties of tilapia. At the end of the study, Nile tilapia gained 235.54 g, blue tilapia
gained 592 g, MC tilapia gained 417 g and FR tilapia gained 105 g. Three temperature reduction regimes were used to evaluate cold tolerance of tilapia varieties and hybrids. The rapid regime consisted of a 0.5 C reduction every 5 hours. Moderate and gradual regimes consisted of 1 C reductions every 24 and 48 hours, respectively. Rapid reduction resulted in mortality of blue, Nile, MC and FR tilapia around 8 C. The most cold-tolerant varieties under the rapid reduction were a strain of FRT selected for cold tolerance and the Nile x blue hybrid, both of which tolerated temperatures of 4 C. A study was designed to evaluate the growth, survival and feed conversion efficiency of six varieties of tilapia in brackish and freshwater mesocosms. Significant variety effects and variety by salinity interactions were determined for both growth and survival.
Impacts
Tilapia production in brackish water can be of particular benefit to shrimp producers and other coastal aquaculturists as an additional marketable product. The combined environmental tolerances of temperature and salinity are also of importance in assessing the risk of establishment of tilapia populations in coastal habitats should they be accidentally or purposely introduced. This research would have global implications, inasmuch as tilapia is currently the second-most widely cultured fish on the planet, exceeded only by carp. International demand for high-quality tilapia fry and fingerlings would fuel increased exports from Louisiana, while high-performing lines would serve to lower production costs and expand markets for domestic producers. The increased ability to utilize tilapia as a filter-feeding species in polyculture systems, without risk of establishing feral populations, would provide an important management tool for catfish producers throughout the
country, and especially in Louisiana.
Publications
- Herbst, E.C. 2002. Induction of tetraploidy in Zebrafish Danio rerio and Nile tilapia Oreochromis niloticus. Masters thesis, Louisiana State University, Baton Rouge, Louisiana. 127 pages.
- Herbst, E.C., Poleo, G.A., Lutz, C.G. and Tiersch, T.R. 2002. Induction of tetraploidy in zebrafish. Page 148 in: Book of Abstracts, Aquaculture America 2002. World Aquaculture Society, Baton Rouge, Louisiana. (Abstract)
- Nugon, R.W. and Lutz, C.G. 2002. Comparison of the salinity tolerance between Mississippi Commercial tilapia, Florida Red tilapia, Nile tilapia O. niloticus, and blue tilapia O. aureus juveniles. Proceedings of the Annual Meeting of the Louisiana Academy of Sciences. (Abstract)
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