Three discrete generations of GIFT fish (Nile tilapia strain, Oreochromis niloticus; a total of 10,065 fish with pedigree and phenotypic information) were tested in pond and cage culture environments to determine genotype by production environment interaction between both environments in Malaysia. Live weight (selected trait), standard length, body depth and width were recorded. A bivariate animal model was used to estimate variance and covariance components, whereby the homologous body traits in pond and cage environments were treated as genetically distinct traits.
Genetic improvement through selective breeding has been used for millennia on crops and livestock, but up until the 1980s, little had been done to utilize this process for farmed fish. In response to the inadequate supply of tilapia seed and the deteriorating performance of the fish in many aquaculture systems in Asia, WorldFish and partners began the Genetic Improvement of Farmed Tilapia (GIFT) project to develop a faster-growing strain of Nile tilapia (Oreochromis niloticus) that was suitable for both small-scale and commercial aquaculture.
Competition for resources is common in aquaculture, which inflates the variability of fish body weight. Selective breeding is one of the effective approaches that may enable a reduction of size variability (or increase in uniformity) for body weight by genetic means. Competition for resources is common in aquaculture, which inflates the variability of fish body weight. Selective breeding is one of the effective approaches that may enable a reduction of size variability (or increase in uniformity) for body weight by genetic means.
The aims of this study were the estimation of genetic parameters for survival rate from tagging until harvest and the evaluation of the correlated response in survival rate to selection for harvest weight in the genetically improved farmed tilapia(GIFT) strain.
The aim of this study was to examine genetic variation in reproductive traits and to estimate correlated responses in such traits to selection for high growth rate in the GIFT strain of Nile tilapia (Oreochromis niloticus).
Genetic parameters and selection responses were obtained for harvest body weight of blue tilapia (Oreochromis aureus) from data collected over three generations in a selected population. A total of 18 194 records representing 186 sires and 201 dams were used in the analysis. Within generation heritability estimates for harvest body weight ranged from 0.18 to 0.58. When data from more than one generation were included in the analysis, heritability estimates became more stable (0.33–0.40) and it was 0.33 when all data were included in the analysis.
The main objective of this paper was to report more reliable estimates of the genetic variation and the genotype by test environment interaction for harvest body weight in the GIFT population in the Philippines than could be obtained from the base population by using the data from the five generations following the base population and that covers a wider span of test environments than the later experiments referred to above. Included are also estimates of the genotype by sex interactions for body weight.
The maintenance of reference populations of Tilapia is discussed, examining genetic considerations to be taken into account to conserve the gene pool to prevent genetic drift and prevent detrimental levels of inbreeding. The importance of knowledge of the proper effective breeding number and its use in management of the reference population is described.
Solomon Islands has a population of just over half a million people, most of whom are rural-based subsistence farmers and fishers who rely heavily on fish as their main animal-source food and for income. The nation is one of the Pacific Island Counties and Territories; future shortfalls in fish production are projected to be serious, and government policy identifies inland aquaculture development as one of the options to meet future demand for fish.
Genetically improved farmed tilapia (GIFT) has undergone ten generations of selection for harvest body weight in Malaysia, but there have been no reports on genetic parameters for flesh characteristics for this strain. In this study the effects of selection for increased harvest body weight on flesh chemical composition (protein%, fat%, moisture% and pH) as well as in colour, were investigated in fillets from fish of the GIFT strain.