Endogenous excretion of Siberian sturgeon,

The pattern of ammonia excretion was examined in the Siberian sturgeon, Acipenser baeri, during starvation. For different weight groups (60 g to 2 kg), this excretion decreased rapidly to reach a constant level of 32 mg NH4-N.kg-1.day-1 after 8 days of fast. This minimum is an estimation of the Endogenous Nitrogen Excretion (ENE). No diurnal pattern was observed in the ammonia excretion or oxygen consumption (28.6 ± 3.2 mg O2.kg-1.h-1, mean ± sd) of fasted fish. These data appear to indicate that the basal metabolism is very low in the Siberian sturgeon and that the nycthemeral cycle is only the result of exogenous nutrition