Résumé
When the Adriatic sturgeon Acipenser naccarii was exposed to progressive hypoxia under static conditions, it exhibited a linear decline in O2 uptake, behaving as an 'oxyconformer'. When, however, it was allowed to swim at a low sustained speed, it could regulate O2 uptake down to a mean ±s.e. critical (Pcrit) of 4·9 ± 0·5 kPa (n= 6). At moderate levels of hypoxia, static fish exhibited significant reductions in arterial blood O2 content, and increases in plasma lactate, which were not observed in swimming animals.