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Tilapia Genetic Strains and Hatchery Technology

Artículos y entrevistas04 de julio de 2012

Genetic improvement program mes enable a more profitable industry to benefit from the increased popularity of tilapia as a glo bal food commodity.


With tilapia being such a diverse group of over 100 species, surprisingly only a handful of species are cultured commercially and only one species, the Nile tilapia, Oreochromis niloticus, accounts for 95% of global production

Genetic improvement program­mes enable a more profitable industry to benefit from the increased popularity of tilapia as a glo­bal food commodity. Production world­wide reached 3.23 million t in 2011 and is steadily growing. The Philippines is at the centre of many of these genetic improvement programmes.

Tilapia fry prices vary around the world, ranging from below US$0.01 in Asia to over US$0.10 in the Americas and up to US$0.20 in Europe, reflecting costs of production and availability of fry. In Egypt and other seasonal markets, fry prices can be 50% higher at the start of spring, compared to the height of sum­mer when everyone has fry available.

Tilapia farming and supermale tecnology

Most commercial farms only grow male tilapia, which grow much larger and faster than females and this was initially achieved through manual hand-sexing of the fingerlings, and discarding the females, which was labour intensive, inconsistent, and wasteful.

It was then found that certain hybrids between different tilapia spe­cies (O.niloticus and O.aureus) gave very high % male progeny. The down­side with this technique was that it required hatcheries to hold two separa­te stocks of tilapia species, and as the purity of tilapia stocks deteriorated, the technique became unviable.

Researchers then discovered that tilapia fry, when fed male sex hormones for the first month after hatching, were able to change sex, from 50- 50 male to female ratio, to ratios of almost 100% male fry. This is a highly variable technique due to hormone purity and operator experience. One of the major challenges facing the industry is that use of Methyl Testosterone will be phased out. This is overcome by the latest technology to effectively provide all male fry - the YY Male Technology developed by Fishgen. After many years of research in the UK and in the Philippines, Fishgen produced supermale tilapia which had two Y chromosomes instead of the usual Y and X chromosome (females have two X chromosomes). These supermales produce only male fry addressing the problems of a future ban on hormonal sex reversal.Tilapia linesDeciding on which commercial strain of tilapia to use in a new tilapia project can be daunting, and there are many commercial stocks available globally.

The farm’s location can have a deciding influence as there are restrictions on importation of some strains from some countries, to minimise disease and biodiversity issues particularly in Africa where there are many unique endemic strains of tilapia, requiring protection from contamination by the careless introduction of new genetic lines, where escapees could interbreed or outcompete with the pure endemic species.There are currently 4 main genetically improved commercial lines that are globally distributed and proven to be fast growing.

The biggest genetic improvement programme was the GIFT project (Genetically Improved Farmed Tilapia) originally produced from 8 strains of the Nile Tilapia collected from Africa in the 1980’s, and after extensive breeding programmes carried out in the Philippines by ICLARM (Now World Fish Center) a new strain was produced and distributed globally. World Fish Center has moved to Penang, Malaysia now and the breeding programme is still carried on in both Malaysia and the Philippines.

The commercial rights to a recent GIFT genetic line was sold to Genomar (a Norweigian Venture Capital Genetic Improvement company) a few years ago and is now marketed globally as Genomar Supreme tilapia (GST) and the processed fish as TRAPIA ensuring full genetic traceability of their products to the food industry. Since then the Philippines have carried on with their own Genetic Improvements of the GIFT line and market the GIFT Excel line now.

These lines are all based on the original genetic stocks collected in Africa in the 1980’s.Another well-known stock is the Chitrilada strain, farmed extensively in Thailand, and originated as a gift to the King of Thailand by the Emperor of Japan in 1965, and was maintained as a pure line in the Royal Jitralada Palace in Bangkok before being distributed throughout the country by the Thai Department of Fisheries in 1967. Since then it has been improved by selective breeding programmes and is now widely farmed in South and Central America, particularly Mexico and Brazil. The only other tilapia genetic line commercially used extensively around the world is the YY Supermale strain, developed by Fishgen in the UK.

This stock is also based on the Nile Tilapia from Egypt, but the main difference between this line and all the others available, is that no hormones are required to sex reverse the fry for growout, as the YY supermale has been specifically bred to sire only male offspring.Tilapia hatcheries The hatchery systems are diverse with cost of construction and production of tilapia fry varying enormously, from basic pond hatcheries in tropical countries costing almost nothing, to high cost high tech biosecure indoor recirculation systems.

The simple broodstock ponds have a shallow area around the edge where the fry once released from the female’s mouth, tend to congregate in tight shoals and are collected with large dip nets on a daily basis. Larger hatcheries use lined ponds in polytunnels give better temperature control, biosecurity and predator protection and the fry are incubated by the female which is less efficient than removing the fertilised eggs from the female’s mouth and using artificial incubators to hatch the fry.Many of the world’s largest tilapia hatcheries are in Asia, where 75% of global tilapia production takes place, use Hapa-based production systems, where the broodstock are stocked in long hapas (Net pens) and the eggs are harvested from the female’s mouth every 5 days.

This is done by opening the buccal cavity of the female and gently rinsing the eggs out of the mouth into a bucket. Importance of fingerlings productionWith global tilapia production still growing steadily, hatcheries are also expanding to provide fry for the grow-out farms and some of the biggest hatcheries now have the capability to produce 1 million fry per day.

The main tilapia producing countries are China, Egypt, Thailand, Indonesia, Philippines, Costa Rica, Ecuador, Mexico and Honduras. There are large hatcheries in all these countries but the biggest farms are vertically integrated units which produce their own fry to minimise biosecurity issues and ensure supply of fry. Rapidly expanding importers of tilapia are Russia and the Middle East, but as China becomes far wealthier, consuming more tilapia domestically, price increases and possible shortages for tilapia are probable. With the tilapia market firmly established and growing globally, future challenges for tilapia will be finding new markets and coming up against stiff competition from Pangasius imported from Vietnam, especially in European markets which was at one time seen as the new dawn for tilapia producers around the world.

 



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