GENOTYPE AND ENVIRONMENT - A COMPARATIVE-EVALUATION OF 4 TILAPIA STOCKS IN FIJI

The reproductive, survival and growth performance of four tilapia stra ins in Fiji, namely Oreochromis mossambicus (M),'Israel' Oreochromis n iloticus (NI),'Chitralada' O. niloticus (NC) and Red tilapia hybrid (R ) were evaluated in two culture environments currently used in Fiji (i ntegrated and non-integrated farming) for three generations. Results s howed significant differences among strains in all traits. Overall, th e M strain had the highest breeding efficiency and average fecundity b ut the poorest growth rate, The NI strain showed the highest survival and a good growth rate but low breeding efficiency and fecundity. Alth ough the R strain showed a good growth rate in favorable environments, it was prone to stress under less optimal conditions and had a relati vely low survival rate and only average fecundity, The NC strain showe d the best growth rate and feed conversion efficiency, relatively good breeding efficiency but average fecundity and survival. Based on a we ighted performance across all traits, the NC strain was identified as the best performing strain in Fijian conditions. Significant genotype- environment interactions estimated during harvest were due to a strong rank interaction in the R strain and also magnitude interactions in t he NC and NI strains, Growth performance of the M strain showed the lo west response to quality of culture environment. Future approaches to improving tilapia production in Fiji are discussed. (C) 1997 Elsevier Science B.V.