NOTES: Predicting the Lethality of Fluctuating Low Temperatures to Blue Tilapia.

Lower-lethal-temperature bioassays were performed with blue tilapias Tilapia aurea to test the utility of a lethal-dose model for forecasting cold-kill events. We applied the model to predict resistance times of blue tilapias acclimated to 24°C upon exposure to lower lethal temperatures varying between 5° and 13°C. Regression of predicted versus observed logarithmic median resistance times was significant, and the line of perfect agreement fell within the 95% confidence limits on the regression line. However, the model consistently underestimated the resistance time in tests that lasted longer than a few hours, presumably because fish in these tests achieved some downward thermal acclimation. We also applied a second model, developed for predicting upper incipient lethal temperatures, to the cold-resistance data from blue tilapias in an attempt to estimate the lower incipient lethal temperature (LILT) of fish acclimated to 24°C. Although the model's estimate of LILT, 14. 1°C, is reasonable, there is still concern about the model's applicability to cold-resistance data. [ABSTRACT FROM AUTHOR]