Oxygen requirements of striped bass, Morone saxatilis, were studied at 0 and 10‰ salinity using combinations of handling and constantly decreasing oxygen concentrations. Effects of handling and salinity on oxygen requirements were negligible or absent. Successive and merging patterns of behavior at low oxygen concentrations were: restlessness, spasmodic swimming, surfacing, inactivity, equilibrium loss, and death. Mean oxygen levels with 99% confidence limits at restlessness, inactivity, equilibrium loss, and death were 1.81 ±.10, 1.28 ±.10, 0.95 ±.06, and 0.72 ±.04 mg/liter. Virtually no fish exhibited these behavior patterns until oxygen declined to 3.12, 2.19, 1.44, and 1.04 mg/liter, respectively; nearly all fish did at 0.91, 0.66, 0.62, and 0.50 mg/liter, respectively. Size of fish did not affect oxygen levels at death and equilibrium loss.Ventilation rate was maximum at 2.0–3.0 mg/liter and declined at lower concentrations. Amplitude was maximum at the beginning of inactivity then declined. Because short-term respiratory failure occurred at equilibrium loss, this behavior probably represents oxygen levels that would cause an abrupt fish-kill. Long-term respiratory failure at inactivity indicated that death would follow a period of resistance.There is no sharp distinction between suitable and unsuitable oxygen concentrations, because duration of exposure determines the intensity of the result even at lethal levels. Onset of restlessness (about 3 mg/liter at 16–19 C) probably represents the minimum permissible oxygen level for normal existence. Even this may be insufficient to maintain optimum populations of striped bass.
Reconciling nuclear microsatellite and mitochondrial marker estimates of population structure: breeding population structure of Chesapeake Bay striped bass (Morone saxatilis)