Changes of oxygen consumption rates in response to various environmental factors and different anesthetic methods in juvenile hybrid sturgeon, Acipenser baeri♀×Acipenser schrencki♂

Abstract

Live fish transportation plays a crucial role in realizing the value of aquaculture in sturgeons. However, hypoxia and hypercapnia are the major issues during the high-density transportation of live fish. Therefore, monitoring the changing environmental factors (such as water temperature, salinity, and pH) or anesthesia methods (MS-222, dissolved CO2, or low-voltage direct electrical current), which can potentially alter the oxygen consumption of fish, are crucial for a better understanding of the necessary conditions for live fish transportation. A semi-open respirometry system was used to quantify the oxygen consumption and respiration frequency of hybrid sturgeon (Acipenser baeri♀×Acipenser schrencki♂). The results indicate that the oxygen consumption rate and respiration frequency of hybrid sturgeon increased linearly with water temperature from 1.4 °C to 25°C. The oxygen consumption rate of hybrid sturgeon increased with the increase of salinity in the range from 3 to 10 ‰ in 9 hours (P < 0.05). Respiration frequency decreased but did not affect the oxygen consumption rate when pH was from 8.1 to 9.8. Exposure to low-voltage direct electrical current ranging from 0.4 to 1.0 V/cm significantly increased the respiration frequency (P < 0.05). The oxygen consumption rate maintained below 1 mg/(g·h) when CO2 concentration ranges from 8.5 to 67.85 mg/L. Compared with the change of oxygen consumption rate and respiration frequency with MS-222 at the range from 5 to 30 mg/L, immersion of fish into more than 8.5–67.85 mg/L dissolved CO2 in water could as an alternative anesthetic method for hybrid sturgeon. These findings in the study may contribute to the culture, live fish transportation, and basic research in hybrid sturgeon.