ストライプトバスの成長に及ぼす溶存酸素の影響

Abstract

Experiments were carried out to examine the effect of nearly constant dissolved oxygen con-centrations, both below and above the air saturation level, on the growth of young striped bass (body weight 2.9-15.0g).Fish were reared for 8 days in 5 different tanks. Each of these tanks had a volume of 16 liters. These tanks were continuously supplied with sea water having different dissolved oxygen con-centrations. Oxygen concentrations were controlled by bubbling nitrogen or oxygen gas through the inflowing water. During the experiments water temperature fluctuated between 20.9 and 27.2°C and the chlorinity varied from 12.16 to 18.38%. Fish were fed three times a day with commercially available, crumbled pellet for young ayu-fish.When the dissolved oxygen concentration was less than about 53% in air saturation, the growth rate and the food conversion efficiency increased remarkably with the increase of dissolved oxygen. The increase of feeding rate was found to be gradual upto 60% in air saturation. Nearly the same levels in the growth rate and food conversion efficiency were observed, when the dissolved oxygen concentrations ranged from 53 to 250% in air saturation. In the case of feeding rate nearly same level was observed, when the dissolved oxygen concentration ranged from 60 to 250% in air saturation. No clear effect of oxygen-supersaturation was observed.