Determination of salinity tolerance limits of tilapia, Oreochromis mossambicus, for use in tuna line fishery

[摘要] ENGLISH ABSTRACT:Many species of tilapia such as Oreochromis mossambicus areeuryhaline, able to adapt to different salinity waters. Their ability towithstand high salinity levels has given rise to the possibility of usingtilapia as baitfish for tuna line fishery. The purpose of the study was todetermine the survival rate of tilapia O. mossambicus during directtransfer from freshwater to the salinity levels of 0, 15, 20, 22.5, 25, 27.5,30, 32.5, and 35 ppt. The data was analysed through means ofunivariate ANOVAand regression analysis.O. mossambicus showed no mortality to all salinity regimes up to25 ppt. Mortality was observed at 27.5 ppt, with 100% mortality at 35ppt. LC 50 and LC 90 were found to be 30.5 and 34.2 ppt, respectively.The results indicate that tilapia (0. mossambicus) will survive a directtransfer to salinities up to 25 ppt. acclimation will be required in theevent of transfer to salinity levels above 25 ppt, in order to preventsignificant levels of mortalities.

[发布机构] Stellenbosch University