During the development of GIFT in the Philippines, responses to selection for improvement in weight at harvest (% gain over the previous generation) over five generations of selection were 19.1%, 13.5%, 9.2%, 17.8%, and 6.2%, respectively, totaling 65.8%.27 These results have not yet been adequately published in peer-reviewed journals, and remain somewhat controversial. The main point at issue is the validity of control values used for comparisons between and across generations. AKVAFORSK and the WorldFish Center are currently reanalyzing the data from this work, and further publications concerning responses to selection are expected in 2005.28 Critics have noted that the synthetic base population itself, before any selective breeding, was reported to have a 60% advantage in harvest weight over widely farmed Philippine strains (footnote 27). This could be mostly attributed to the crossbreeding of strains during development of the synthetic base population. Together with the subsequent responses to selection, this represents a claimed growth performance advantage of about 125% for GIFT over Philippine farmed strains. In other words, in comparable environments, GIFT should reach harvest size in less than half the time taken by unimproved tilapia strains.However, subsequent comparisons (including those during DEGITA) of the performance of GIFT and other Nile tilapia farmed in Asia show much lower advantages for GIFT and, in some cases, show insignificant differences. This is because the results of any such comparison among strains are valid only for the environment (location, time, and farming system) where they are obtained. A wide range of differences in performance between GIFT and nonGIFT tilapia in Asia is to be expected, given the region’s history of tilapia movements and variable attention to broodstock management, as well as local adaptation of farmed tilapia strains. Despite these complexities, the developers of GIFT demonstrated that selective breeding produced progressively faster growing generations of Nile tilapia, and that application of genetics to tilapia farming—and by inference to tropical aquaculture in general—can result in substantial and rapid development of improved Nile tilapia strains.