Collaborating Institution
Asian Institute of Technology, Thailand
     Amrit Bart

Regional Agricultural Research Station, Tarahara, Nepal
     A.K. Rai
The University of Michigan
     James S. Diana

Objectives
1) Select one broodstock group of Nile tilapia from AIT and carry out on-station production trials (fertilization only, fertilization and feeding) in Nepal (Year 1).

2) Introduce hapa-based sex-reversed tilapia seed production technique - On-station trial (Year 2).

3) Carry out farm growth trials of above stock (mixed-sex and sex-reversed) utilizing CRSP best management protocols and experience in southern and central Nepal (Year 2).

Significance
The CRSP studies have made significant contributions to determining the optimal fertilization regimes for warm and cool weather conditions (Brown et al., 2000; Veverica et al., 2001), feeding (Diana et al., 1996), production of monosex populations (Green and Teichert-Coddington, 1994; Gale et al., 1999; Phelps and Warrington, 2001) and polyculture with other species (Szyper and Hopkins, 1997). The tilapia production industry has benefited a great deal from these and other studies, particularly in Southeast Asia. Problem-based research studies at AIT in Thailand has played a critical role in providing technical and research support that has facilitated the industry to expand in many different areas.

Additionally, we have found that low-input tilapia production has especially benefited resource poor farmers in the Southeast Asia. Small-scale tilapia growers also tend to consume their own fish, thus increasing high-quality protein in household diets. Unfortunately, some of the poorest countries in Asia, including Nepal, have not received direct benefits of PD/A CRSP presence in Thailand. Although fish is highly desirable in Nepalese diet, per annual consumption is only 1 kg per person (Edwards, 1998). Nepal, one of the poorest nations suffers severe malnutrition problems especially among young children. Tilapia, lauded as a low input aquaculture species, has the potential to provide cheap protein in children's diet if the culture technology is developed to benefit small-scale farmers.

Lack of tilapia production in Nepal is partly due to previous government policy to not introduce exotic species that might have negative impact on the local biodiversity and indigenous species. Nile tilapia Oreochromis niloticus was first transported to Nepal in 1985 and held in various government research stations for research and development purposes (Pullin, 1986; Singh, 1995). The origins of these strains are unclear and further development work has not been done on tilapia culture. The government has now realized that there is an increasing interest among farmers to raise tilapia, which is indicated by import of seed from neighboring India. A number of farmers have stocked this species in their ponds and hapas. This uncontrolled and unchecked introduction of tilapia is seen as having a negative impact on small-scale farmers' livelihood because the fish they use to begin aquaculture systems are of poor quality. The Fisheries Research Division, Godawari of the National Agricultural Research Council (NARC) has been charged with the responsibility to develop a production package that includes importation of appropriate strains, seed production using modern techniques and grow-out technology that is suitable to low input conditions of southern and central Nepal.

PD/A CRSP at AIT has many years of research and experience in pond/hapa-based tilapia production, which could be reasonably adapted to sub-tropical conditions of Southern Nepal. This activity proposes to assist in transfer of PD/A CRSP developed technology on tilapia culture to Nepal through on-station trials with feeding and fertilizing, as well as production of sex-reversed and mixed-sex seed in hapas.

Anticipated Benefits
Successful introduction of tilapia culture techniques is expected to:

1) Increase fish production and protein levels in the household diet of rural poor;
2) Prevent uncontrolled transport of low quality seed from India; and
3) Assist in identifying research needs and facilitate future CRSP activities in Nepal.

Activity Design

Location: NARC research facilities, Rampur, Nepal.

Methods

Production Trials

Earlier trials in PD/A CRSP by Diana et al. (1996) demonstrated that initiation of feeding after 80 days produced the same yield as feeding from day zero. Fish given feeding after day 80 also reached the same expected size, with some time delay. An on-farm trial was conducted by Brown and Bolivar (2000) in the Philippines based on Diana et al. (1996) report and observed similar results, particularly when economic returns were considered. We intend to follow similar trial in Nepal using on-station facilities. On station trials will be conducted on Improved and selected lines (GIFT 6^th generation selects) of tilapia.

Nile tilapia fingerlings (35 days old, 1,200 total) will be transported to Nepal where they will be placed in several 50-m² ponds at 4 fish/m². Half of the ponds will be fertilized weekly with urea ammonium sulfate at a rate of 28 kg N ha^-1 wk ^-1 and 5.6 kg P ha^-1 wk^-1. The other half of the ponds will be fertilized and fed diet starting on the 80^th day. The diet will consist of 67% rice bran and 33% fishmeal applied at 3% BWD until harvest. A sample of 50 fish will be removed every two weeks to measure average weight of fish. Water quality will be monitored according to standard methods (APHA, 1980; PD/A CRSP, 1992).

Fish will be harvested after 180 days. Variables measured will include total number of fish and bulk-weight. Final total feed given, mean weight, daily weight gain, gross yield and survival rates will also be calculated. Data will be analyzed by paired t-test.

Seed Production Trials

Production of mixed-sex and monosex fry and fingerlings will be based on AITs hapa-based model. Broodfish will be selected from the pool of fish in the above trial and stocked in hapas in 200-m² ponds at a rate of 4 fish/m². Broodfish will be fed 67% rice bran and 33% fishmeal at 2% BWD. Female fish will be checked every 4-5 days for eggs. Fertilized eggs will be pooled by development stages and separated for incubation.

A low-cost flow-through incubation tray system will be constructed to allow sufficient flow rate to keep fertilized eggs well oxygenated and moving (Little 1986). Hatched fry at three days after yolk sac absorption will be divided into two groups. One group will be fed with commercially available 17a-methyltestosterone coated diet and the other group will receive no hormone. Larvae will then be fed with 67% rice bran and 33% fish meal at 5% BWD up to 15 days and 4% up to 30 days. Both groups will be raised up to 120 days and sex ratios compared between these two treatments. Additionally, fecundity, fertilization rate, hatch rate, and survival rate data will be assessed.

Economic profitability will be compared between fertilized pond and fertilized + fed pond.

Regional Integration

This initial activity is expected to lead to many problem-based and demand driven research in the region. Successful introduction and integration of tilapia culture may be used as a model for other poor countries with similar environmental conditions such as north India, Bhutan, Bangladesh, and Myanmar.

Schedule
Production trial: August 2001 to March 2002
Seed production trial: April 2002 to January 2003
Report submission: 15 March 2003

References
Diana, J.S., C.K. Lin, and Y. Yi, 1996. Timing of supplemental feeding for tilapia production. J. World Aquacult. Soc., 27:410­419.

Edwards, P., 1998. AIT mission to Nepal. AARM News Letter, 3(1):15­17.

Gale, W.L., M.S. Fitzpatrick, M. Lucero, W.M. Contreras-Sánchez, and C.B. Schreck, 1999. Production of all male populations of Nile tilapia (Oreochromis niloticus) Masculinization of tilapia by immersion in androgens. Aquaculture, 178:349­357.

Green, B., and D. Teichert-Coddington, 1994. Growth of control land androgen-treated Nile tilapia, Oreochromis niloticus (L.), during treatment, nursery and grow-out phases in tropical fish ponds. Aquaculture and Fisheries Management, 25:613­621.

Little, D.C., 1989. An evaluation of strategies for production of Nile tilapia, Oreochromis niloticus, fry suitable for hormonal treatment. Ph.D. dissertation, University of Stirling, UK.

Phelps, R.P. and R.L. Warrington, 2001. Methods for the contribution for the male and female genome to sex inheritance. In: A. Gupta, K. McElwee, D. Burke, J. Burright, X. Cummings, and H. Egna (Editors), Eighteenth Annual Technical Report, Pond Dynamics/Aquaculture CRSP, Oregon State University, Corvallis, Oregon, pp. 37­42.

Pullin, R.S.V., 1986. Aquaculture development in Nepal- Pointers for success. Naga, The ICLARM Quarterly, January 1986:9­10.

Shrestha, M.K. and R.C. Bhujel, 1999. A preliminary study on Nile tilapia, Oreochromis niloticus, polyculture with common carp, Cyprinus carpio, fed with duckweed, Spirodela, in Nepal.

Szyper J.P. and K. Hopkins, 1997. Carp/tilapia polyculture on acid-sulfate soils. In: D. Burke, B. Goetze, D. Clair, and H. Egna (Editors), Fourteenth Annual Technical Report. Pond Dynamics/Aquaculture CRSP, Oregon State University, Corvallis, Oregon, pp. 157­160.

Veverica, K.L, J. Bowman, and T. Popma, 2001. Global Experiment: Optimization of nitrogen fertilization rate on freshwater tilapia production ponds. In: A. Gupta, K. McElwee, D. Burke, J. Burright, X. Cummings, and H. Egna (Editors), Eighteenth Annual Technical Report, Pond Dynamics/Aquaculture CRSP, Oregon State University, Corvallis, Oregon, pp. 13­21.