World Aquaculture December 2020

62 DECEMBER 2020 • WORLD AQUACULTURE • WWW.WA S.ORG Bureau of Fisheries and Aquatic Resources (BFAR), University of the Philippines-Marine Science Institute, and the International Center for Living Aquatic Resources Management (ICLARM, nowWorldFish). The project was funded by the United Nations Development Program and the Asian Development Bank. Four Nile tilapia strains fromGhana, Egypt, Senegal and Kenya were crossbred with four Nile tilapia strains from the Philippines (i.e. tilapia strains that originated from Israel, Thailand, Singapore and Taiwan). A total of 25 groups with better growth performance were used to create a synthetic base population that later produced fishes with greater growth and survival in different culture systems (Eknath et al . 1993, Ordoñez et al. 2014). There was an increase of 12-17 percent gain in growth rate over five generations, which accounts to 60-85 percent of cumulative increase over the initial population (Ordoñez et al . 2014) with the strains coming from Africa, with exception of the Ghana strain (Ansah et al . 2014). With demonstration of the substantial increase in potential fish yield, many countries expressed interest in obtaining the GIFT strain (Dey et al . 2000a). Successive breeding researchers followed and were named the “sons of GIFT” (Ordoñez et al . 2014). GST Strain The GIFT Foundation International teamed up with the Norwe- gian aquaculture biotechnology laboratory GenoMar in 1999. Geno- Mar applied DNAmarker-assisted selection for improvement of the GIFT strain as a replacement of physical tagging to increase differen- tial selection (Ansah et al. 2014, Muallil et al . 2014, Romana-Eguia et al . 2019). As GenoMar is private and their technology is proprietary, not all genetic selection techniques were disseminated to the public (Ponzoni et al . 2010). Genetic linkage maps were created to reveal the genes that are economically important. Some of the influential traits for economic gain identified were sex determination, salt toler- ance, color, body shape and growth (Gjoen 2001). In 2001, the strain produced by GenoMar known as GST was distributed and dissemi- nated across Latin America and Southeast Asia (Ansah et al . 2014). FaST Strain The FaST strain was generated using within-family rotational mating and hybridization using size-graded and pre-selected stock (Bolivar and Newkirk 2002, Muallil et al . 2014, Romana-Eguia et al . 2019). The selection fromwithin family occurred for 12 generations with the objective of increasing body weight at 16 weeks of age. Selected strains fromwithin-family mating, together with the GIFT strain, and a commercial strain from Israel were grown in ponds, tanks and hapa net enclosures in ponds. There was an increase in body weight of the selected strain compared to GIFT and Israel strains, especially in tanks (Bolivar and Newkirk 2002). In a study by Mualil et al . (2014), the three tilapia strains were compared in terms of their fluctuation asymmetry (FA). In the presence of genetic and environmental stressors, FA can serve as an Collected tilapia eggs being prepared for fertilization with frozen milt (Photo: J.A. Ragaza). In rural areas, GET-EXCEL fingerlings are sold for US$ 0.06 each for backyard and large-scale tilapia farming. The banding patterns are already visible at this stage (Photo: J. Consuelo).