DEVELOPMENT OF TILAPIA FOR SALINE WATERS IN THE PHILIPPINES

Four Oreochromis species were used in Phase 1 study. Progenies from the 28 cross combinations (5 purebreds and 23 crossbreds) were evaluated in 10 environments with different salinity levels and agro-climatic conditions using communal rearing concept. Data obtained after 120 days of culture revealed that among the different cross combinations reared across environments, pure cross of O. niloticus FaST gave the highest gain in weight and S4xS2 (O. niloticus GIFT x O. aureus) gave the highest survival. Positive heterosis was observed in crosses between S2xS1 (O. aureus x O. spilurus) and S3xS5 (O. mossambicus x O. niloticus FaST) for growth and S1xS3 (O. spilurus x O. mossambicus) and S3xS5 (O. mossambicus x O. niloticus FaST) for survival. Purebreds (except O. mossambicus) showed better performance than hybrids for growth and survival. Positive combining ability of the different strains showed that O. niloticus GIFT and O. spilurus have potential for hybridization when used as dam and sire, respectively. In Phase 2 study, sixteen (16) best performing strain combinations formed the base population. Selected fish were bred and tested in different culture systems namely cage, pond and tank. Result from this study showed that progenies from the cross between (S1xS5) x (S5 x S3) was the best among the top ranking families based on body weight while the cross between (S4xS5) x (S1xS2) was the best in terms of survival. The performance in terms of growth and survival of the different families communally reared in various culture systems was significantly different at P<0.05 level. Not all top ranking families based on body weight were included in the top ranking families based on survival. All hybrid crosses with O. spilurus was included in the top ranking families based on survival