Salinity Tolerance of the Tilapias 'Oreochromis aureus, O. niloticus' and an 'O. mossambicus' X 'O. niloticus' Hybrid

摘要

The ontogeny of salinity tolerance was studied in the tilapias Oreochromis aureus, O. niloticus and an O. mossambicus X O. niloticus (M X N) hybrid, spawned and reared in freshwater. Several indices were employed as practical measures of salinity tolerance: (1) median lethal salinity-96 hours (MLS-96), defined as the salinity at which survival falls to 50%, 96 hours following direct transfer from freshwater to varying salinities; (2) mean survival time (MST), defined as the mean survival time over a 96-hour period, following direct transfer from freshwater to seawater (32 ppt). These ontogenetic changes in salinity tolerance were determined to be more closely related to body size than to chronological age. No consistent relationship was observed between salinity tolerance and condition factor.