Browsing by Author "Fitwi, Biniam Samuel"

Now showing 1 - 1 of 1
  • Thumbnail Image
    Item
    Determination of salinity tolerance limits of tilapia, Oreochromis mossambicus, for use in tuna line fishery
    (Stellenbosch : Stellenbosch University, 2003-12) Fitwi, Biniam Samuel; Brink, Danie; Stellenbosch University. Faculty of AgriSciences. Dept. of Animal Science.
    ENGLISH ABSTRACT: Many species of tilapia such as Oreochromis mossambicus are euryhaline, able to adapt to different salinity waters. Their ability to withstand high salinity levels has given rise to the possibility of using tilapia as baitfish for tuna line fishery. The purpose of the study was to determine the survival rate of tilapia O. mossambicus during direct transfer 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 of univariate ANOVAand regression analysis. O. mossambicus showed no mortality to all salinity regimes up to 25 ppt. Mortality was observed at 27.5 ppt, with 100% mortality at 35 ppt. 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 direct transfer to salinities up to 25 ppt. acclimation will be required in the event of transfer to salinity levels above 25 ppt, in order to prevent significant levels of mortalities.