Preliminary study on tolerance of elver of 5 Anguilla species to ultimate water temperature

We studied the tolerance of elver of 5 Anguilla species (Anguilla japonica, A.anguilla, A.rostrata, A.bicolor pacifica and A.mormorata) to ultimate high and low water temperature as well as their difference. We used natural water temperature as initial temperature (27 ℃ for Anguilla japonica, A.anguilla and A.bicolor Pacifica; 24 ℃ for A.rostrata and A.mormorata), and increased/decreased 1 ℃ every 4 h in high-temperature/low-temperature experiment respectively until all individuals died. The result indicates that the elvers of 5 Anguilla species show different tolerance to ultimate water temperature. The temperature for the highest mortality of A.japonica, A.rostrata, A.anguilla, A.bicolor pacifica and A.mormorata is 39, 38, 37.5, 39 and 38℃, respectively. A.japonica tolerates high temperature best while A.anguilla worst, but the difference is insignificant. A. japonica and A. rostrata tolerate low temperature best and can survive in mixture of ice and water. As for the other 3 species, the temperature for the highest mortality of A.anguilla, A.mormorata and A.bicolor pacifica is 2, 5 and 10 ℃, respectively.