Impacts of Combined Salinity and Temperature Extremes on Different Strains and Species of Tilapia Inhabiting the Watershed of the Salton Sea

Tilapia have relatively rapid osmoregulatory abilities, but the combined stress due to extreme temperature and salinity can negatively affect the survival of the fish. This study compared the tolerance of the California Mozambique Tilapia hybrid (Mozambique Tilapia Oreochromis mossambicus x Wami Tilapia O. urolepis; CA hybrid) from aquaculture and three species of tilapia that currently live in the Salton Sea area: Blue Tilapia O. aureus, Redbelly Tilapia Tilapia zillii, and CA hybrid collected from the sea. The CA hybrid tilapia (both cultured and feral) was the most resistant species across all treatments and could survive salinities up to 60 g/L (parts per thousand). The CA hybrid from aquaculture was the most tolerant to higher temperatures (33-38 degrees C), while the one from the Salton Sea was the most tolerant to colder temperatures (11-16 degrees C). In terms of salinity regimes, the aquaculture CA hybrid and Blue Tilapia survived better at 20 parts per thousand, while the CA hybrid from the sea did best at 45 parts per thousand. The different stocks of tilapia showed very different tolerances, and these results provide valuable information for the future management of the Salton Sea.