Effect of temperature and dissolved oxygen concentration on the metabolic rate of the turbot and the relationship between metabolic scope and feeding demand

Turbot Scophthalmus maximus maximum oxygen uptake following feeding and exhaustive exercise increased from 107 mg O sub(2) kg super(-1) h super(-1) at 6 degree C toc . 218 mg O sub(2) kg super(-1) h super(-1) at 18 degree C, then increased slightly from 18 to 22 degree C to 224 mg O sub(2) kg super(-1) h super(-1). Standard oxygen uptake increased exponentially as a function of temperature from 11 mg O sub(2) kg super(-1) h super(-1) at 6 degree C to 66 mg O sub(2) kg super(-1) h super(-1) at 22 degree C. Gradual reduction in oxygen concentration to 87-90% air saturation at 6, 10, 18 degree C and 100% saturation) had little effect. Metabolic scope attained a maximum of 176 mg O sub(2) kg super(-1) h super(-1) at 18 degree C. Interpolation of the results showed that this value changed little between 16 and 20 degree C. It is suggested that this temperature range is optimal for turbot ofc . 500 g. A comparison with a previous study on feeding demand in intensive farming conditions showed a linear relationship between appetite and metabolic scope. It is concluded that the ability of a fish to supply energy (including the energy requirement of digestive metabolism) above a standard level is a limiting factor in the manifestation of its feeding demand. Copyright 2002 The Fisheries Society of the British Isles. Published by Elsevier Science Ltd. All rights reserved.