Determination on the low lethal temperature tolerance ,oxygen consumption rate and asphyxiation point of juvenile largemouth bass

Abstract:

The tolerance to low water temperature, oxygen consumption rate and asphyxiation point were compared among northern largemouth bass, florida largemouth bass and their reciprocal hybrids. The results were as follows: when the acclimation temperature was 20 ℃ and the rate of temperature decrease was 2 h/℃,the low semi lethal temperatures of northern largemouth bass was the lowest(3.1±0.17) ℃, florida largemouth bass was the highest(5.05±0.21) ℃.One way ANOVA analysis indicated that there were significant differences(P<0.05) in the tolerance to low temperature of four largemouth bass species.The oxygen consumption rate and asphyxiation point of four largemouth bass species were studied.The result demonstrated that,under the natural water temperature(24-27℃), the oxygen consumption rate were 0.136 8 mg/(g·h),0.181 1 mg/(g·h),0.168 1 mg/(g·h) and 0.138 8 mg/(g·h), respectively. There were no significantly difference for the oxygen consumption rate at the four groups in day and night. Under constant temperature 15 ℃,the asphyxiation point of them were 0.33 mg/L,0.40 mg/L,0.38 mg/L and 0.34 mg/L, respectively.There was no significantly difference between the oxygen consumption of the four largemouth bass species(P>0.05).