Taiwan tilapia breeding becomes more precise, molecular markers become a common language between industry and academia

Smart agriculture is not just about having the facilities in place; managing aquaculture species is even more critical. With funding from the Taiwan Fisheries Research Institute's Smart Agriculture 4.0 subsidy, Shengdiao Aquaculture Technology transferred the gene identification technology from the Fisheries Research Institute in 2018 and set up a simple laboratory to test the molecular markers of broodstock, raising the breeding success rate to 100%, enabling effective management of the performance breeding of in-house conservation fish strains and commercial broodstock, and reducing rearing costs.

"In the past, we selected by naked eye and culled unsuitable fish, thinking that if we picked the fish at the top of the pyramid there would be no problem, but it was not accurate enough." Huang Yisheng, chairman of Shengdiao Aquaculture Technology, said that in 2014 Shengdiao transferred the red tilapia TsR strain, using body color differences caused by genetics to breed the needed broodstock. Target broodstock could be selected at the fry stage, without having to wait until the adult stage to see differences in body length, achieving a 95% breeding success rate. In 2018, the gene identification technology was transferred again. After using molecular marker technology to build a database, simply taking a tissue sample was enough to know whether a fish was the target broodstock, raising the breeding success rate to 100%.

Zeng Fusheng, a researcher in the Aquaculture Division of the Fisheries Research Institute who helped Shengdiao learn molecular marker technology, said that when the Fisheries Research Institute transferred six pairs of the seawater tilapia TFS strain to a operator about 3 years ago, it first listed the seawater aquaculture gene as one of the molecular markers. Later, when the operator crossed this strain with in-house broodstock, unsuitable individuals were culled, and finally the offspring they considered more suitable for sale were kept. The Fisheries Research Institute then clipped fins for sampling to determine whether they were the variety previously tracked. If so, the gene sequences of this batch considered to be a good variety were recorded. In the future, seeing a specific marker would indicate it was suitable. "Molecular markers are like an ID card. Because these fish are economic species, we want to keep good traits, but everyone may not describe appearances in the same way. With the help of genes, judgments can be more objective."

Zeng Fusheng explained that these recorded gene sequences only reflect commercial needs and do not necessarily have academic characteristics and definitions. However, academia can use this data to further understand the relationship between genes and traits, and can also continuously track fish species transferred out through already recorded molecular markers. In addition, through this data, when farmers report breeding or aquaculture problems, researchers can communicate effectively with farmers and provide assistance, unlike in the past when farmers used their own set of appearance identification terms that researchers could not understand.

Huang Yisheng recalled that in the past, when communicating with researchers, each side had its own set of terms for judging selected broodstock, and it was difficult to connect them. Now, with molecular marker technology, they no longer talk past each other, and it can be done at the fry stage. Simply clipping a piece of fin and using PCR amplification technology for testing can track the bloodline of the fish, determine its characteristics after growing up for control, save rearing costs, and raise the breeding success rate to 100%.