Endogenous excretion of Siberian sturgeon, Acipenser baeri Brandt

Abstract

The pattern of ammonia excretion was examincd in the Siberian sturgeon, Acipenser bueri, during starvation. For diffcrcnt wcight groups (60g to 2kg), this excretion decreased rapidly to rcach a constant lcvel of 32 mg NH4-N. kg-'. day-' after 8 days of fast. This minimum is an estimation of the Endogenous Nitrogen Excretion (ENE). No diurnal pattcrn was observed in the ammonia excretion or oxygen consumption (28.6*3.2mg O,.kg-'. h-', mean ksd) of fasted fish. Thcsc data appear to indicate that the basal metabolism is very low in the Sibcrian sturgcon and that the nycthemeral cycle is only the result of exogenous nutrition.