Tilapia Aquaculture – An Overview: Selection of Broodstocks and Hatchery Systems

1. Tilapia Aquaculture – An Overview: Selection of Broodstocks and Hatchery Systems Kevin FitzsimmonsUniversity of Arizona, Professor World Aquaculture Society, Immediate Past-President American Tilapia Association, Sec./Tres. Pablo Gonzalez Alanis Universidad Autonoma de Tamaulipas, Professor World Aquaculture Society, Student Liaison Program Coordinator, Aquaculture TIES Hermosillo, Son. Mexico Dec. 2, 2005

2. Tilapia breeds • Proper selection of fish for your type of production system is second most important decision (after marketing) • There are several species, hybrid strains, and breeding programs available • Goals are fast growth, good FCR and mostly male fish • Must determine if farm will buy fry or fingerlings or attempt to maintain own hatchery

3. Tilapia species and breeds • O. niloticus (Nile Tilapia) – Most commonly used tilapia 70-75% of global production • O. aureus (Blue Tilapia) about 5% of global production • O. mossambicus - (Mossambique or Java Tilapia) about 5% of global production • Red hybrid strains - O. mossambicus and/or O. urolepis-hornorum (Wami River Tilapia) crossed with O. aureus and/or O. niloticus) about 20% of global production

4. Tilapia species and breeds • Match fish to production system • Brackish water – Red hybrid strains • Pond systems – O. niloticus or red strains • Cage systems – O. niloticus or red strains • Intensive (tanks, raceways or recirculating systems) - O. niloticus or red strains • Cooler temperatures – O. aureus or hybrids • South Africa and California (only O. mossambicus and hybrids)

5. Genetic Improvements in Tilapia (From: Mair, G., 2002)

6. O. niloticus strains and breeding programs • G.I.F.T. - Genetically Improved Farmed Tilapia • Chitralada – From a strain kept at the Chitralada Royal Palace in Thailand • Genomar – A Norwegian-Brazilian breeding program • G.I.F.T.-EXCEL – Additional breeding program continued in the Philippines • At least 3 more family selection programs

7. Red Tilapia strains • Red O. mossambicus mutants found in 1970’s • Backcrossings fixed the mutation • Taiwan, Florida, Israeli, and Stirling (Scotland) strains were developed • These were repeatedly out-crossed to other species (New strains in Jamaica, Arizona, Colombia, Ecuador, Thailand, China, Vietnam) • Many red strains now available, most with high salinity tolerance

8. Methyltestosterone technique • Feed fry with food containing MT (60mg 17α-MT/kg of feed) for 21 days • For product to be sold in US, MT feed should be purchased from approved supplier • Females develop as males, males unaffected • Isotope labeling studies demonstrate that MT in fish is below detectable limits 30 days after last feeding • 90+ % develop as male fish

9. YY technique • Treat fry with estrogen • Males develop as females • These XY females are mated to normal males (XY) • ¼ XX : ½ XY : ¼ YY • XY and YY males are progeny tested to XX • Fathers of all male fry (XY) must be YY • YY males can be sold and crossed to normal females (XX) to get almost all male progeny (XY)

10. The YY male technology (GMT®) (From: Mair, G., 2002)

11. YY technique • FishGen, is a UK based company which sells YY males and fry from YY male hatcheries in several countries • Genetically Male Tilapia (GMT) is their brand name • Food fish are two generations removed from being treated with hormone and can be considered organic. • Technique could be copied, but hatchery would need several years and many qualified biologists to develop a program

12. Hybrid crosses • Several inter-specific crosses yield high proportion of males (70-90%) • Requires maintenance of two pure species breeding lines • This technique was developed in Israel and Chinese claim to do this with GIFT niloticus crossed with O. aureus. However, use of MT is suspected.

13. Hatchery styles • Normally stock 1♂ and 3♀ • Eggs are incubated by female • Eggs can be collected and hatched in jars or trays • Or hatched by mother and fry collected when free swimming

14. Dr. Raul Ponzoni and World Fish Center program in Malaysia .

15. Typical spawning or fry rearing hapas

16. Pond spawning vs. tank spawning • Pond or hapa rearing for large numbers • Tank spawning for small numbers and directed rearing programs

17. Jar and trayegg hatching • Jar hatching better for large numbers with little supervision • Tray hatching better if labor is abundant and high survival is important

18. Technologies to reduce externalities(MT use and discharge) • Reduce or eliminate MT use (mixed sex, cages, YY, hybrids, salt-water culture) • Use phytochemicals to induce sex change (still experimental) • Remove effluent MT with carbon, UV, or ozone

19. Post hatch • Swim-up fry allowed to leave hatching vessel • Usually collected in screened buckets or trays • Start sex reversal or start normal feeding in hapas

20. Fry moved to pre-growout around 1 g