Physiology of Finfish and Shellfish (2+1)

4.3.2.12 Metabolicrate

It is the measure of the energy used by an animal in a given time period or it is a measurement of the conversion of chemical energy into heat or heat energy released per unit time.

Three levels of metabolism will be distinguished here. Following the usage now currently among a number of fisheries workers, these will be termed "basal ","standard" and “active" levels of metabolism.

The basal metabolism or Basal Metabolic Rate is the minimum rate of energy required by the body to keep the organism alive or in otherwords to sustain basic life processes, including breathing, circulation and tissue repair the minimum rate of energy expenditure to keep the organism alive expressed as mg of O₂/kg/hr.

Standard metabolism or Standard Metabolic Rate (SMR) refers to an animal’s resting and fasting metabolism at a given body temperature minimum rate of oxygen consumption of an organism at rest in the post-absorptive state (when there is no food in the gut) expressed as mg of O₂/kg/hr. Standard metabolism is an approximation of the minimum rate for the intact organism.

Active or field metabolism is the maximum rate of energy expenditure at maximum sustained activity rate of oxygen consumption during maximum sustained activity expressed as mg of O₂/kg/hr. It is the average rate of energy utilization as the animal goes about its normal activities, which may range from complete inactivity while the animal is at rest to exerting maximum energy.

Routine metabolism is the metabolic rate of an organism during normal spontaneous activity expressed as mg of O₂/kg/hr.

Most measures of metabolism have been measurements of routine metabolism. Standard and active metabolism has not yet often been measured, and the limits of these have been still less often well worked out.