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

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

Tilapia species and breeds F O. niloticus (Nile Tilapia) – Most commonly used tilapia 70-75% of global production F O. aureus (Blue Tilapia) about 5% of global production F O. mossambicus - (Mossambique or Java Tilapia) about 5% of global production F 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

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

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

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

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

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

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

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

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

Hybrid crosses F Several inter-specific crosses yield high proportion of males (70-90%) F Requires maintenance of two pure species breeding lines F 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.

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

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

Typical spawning or fry rearing hapas

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

Jar and tray egg hatching F Jar hatching better for large numbers with little supervision F Tray hatching better if labor is abundant and high survival is important

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

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

Fry moved to pre-growout around 1 g