This revolutionary fish breeding method promises more yields

As the World Fish Day was marked in November in the sleepy Idangalasi village in Kakamega County, farmers were introduced to an exciting tilapia breeding technology.

Dubbed YY male tilapia technology, it is based on the genetic manipulation of fish sex as opposed to the conventional use of hormones for reproduction.

Principal Secretary in the State Department of Fisheries Mr Micheni Ntiba admiring Private fish ponds in Kakamega County stocked with YY technology breeds. (PHOTO: COURTESY)

On that day, the clarion message from the Principal Secretary in the State Department of Fisheries Prof Micheni Ntiba who launched the project, was that the future of the industry hinged on innovation and technology.

“It is time to exit conventional farming and embrace aqua YY technology because it means economic prosperity for farmers,” he said during the launch.

The brainchild

YY technology is the brainchild of Dr Grahan Mair, an award winning and internationally recognised science leader in sea food industry specialising in aquaculture and genetic breeding programmes.

It dates back to 2001 when Dr Mair working with other scientists concluded that the technology provides a robust, reliable solution to the widespread problems of early maturation, unwanted reproduction and overpopulation in tilapia culture.

In Kenya, Jambo Fish Project are the only supplies of this technology which first came to the country in 2012 and was officially rolled out locally in July this year.

In place to punctuate the message were ultramodern equipment installed at the Jambo Fish project that make the production of male only fingerlings possible without the use of hormones and fertilisation as we know it.

Naturally, males are produced from the fusion of X and Y chromosomes while X and X results in females. But with YY male tilapia technology, one can still get mono-sex fish, which matures fast.

Mr Ntiba came armed with sweet news that the lucrative European market had opened its doors to Kenyan farmed fish. But for that to be realised, there was one rider — application of hormones to fish destined for human consumption was prohibited in the European Union under a formal directive.

The cost

Why the emphasis on male fish? Jambo Fish project general manager Susan Akinyi tells Smart Harvest that male fish especially the popular tilapia grow faster and larger because, unlike the females that spend part of their life carrying eggs in their mouths, thus feeding little, they (male fish) feed robustly and thus grow faster.

For farmers intending to stock their ponds with fish from YY technology, Akinyi explains that the resultant four week old normal XY male cost at most Sh10 a piece.

“They weight about 0.4 grams at four weeks and the cost ranges between Sh7 and Sh10 apiece depending on the weight,” she says.

Dr Eric Bink of Til-Aqua International Ltd in the Netherlands that perfected the novel technology says: “Single sex culture resulting from YY male technology based on genetic manipulation of sex alleviates early sexual maturation, uncontrolled reproduction and over population common in conventional farming.”

He says the technology maintains strain purity in genetically normal males. Explaining how the YY technology works, Dr Bink says it is achieved through a combination of feminisation and progeny to identify the novel YY genotype that sires only XY natural male progeny.

“Feminisation of the YY genotype to get XY females is a vital step in the development of the YY technology on a large scale,” notes Dr Bink.

“This is achievable by irradiation and thermal treatment that avoids the use of hormones at any stage of the production process.”

He points out that YY technology is safer for farm operators because it avoids the health risks associated with the use and handling of hormones that can be harmful to humans if swallowed or absorbed through the skin or inhalation.

“YY male fish technology results in greater fingerling survival rates compared to other sex reversal methods in practice involving hormones and prevent many environmental impact risks such as hormone residues in the production water, units and system waste could have.

Pure gene

“It also reduces ecological impact on wild populations when farmed stocks are released through restocking programmes and accidental escapes.

Experts say the release of hormone sex-reversed tilapia into the wild consists of 50 per cent males with XX chromosomes. Result? The next generation in the ecosystem will have a very high female ratio. The natural balance of sexes in the ecosystem will change dramatically, a situation the local fisherman will dislike, as they will catch only very small fish.

Every technology has two sides of the coin, so what’s the flip side?

The biggest disadvantage for ordinary farmers according to Akinyi is invasion of the pond by strange fish, particularly for farmers with ponds located close to rivers.

“Austere management is imperative for the technology to succeed for the farmers’ optimum benefit because any intrusion by populations from unknown sources can introduce females and haphazard reproduction resulting in uneconomically small fish,” she says.

Investment in hatcheries is a prohibitive venture cost-wise which is a disadvantage due to limited sources of fingerlings for farmers needing them.

“Accessibility to the fingerlings would be easier for farmers if hatcheries were many and within easy reach of farmers,” she says.