Recent advances in telemetry for estimating the energy metabolism of wild fishes

Abstract

Metabolic rate is a critical factor in animal biology and ecology, providing an objective measure that can be used in attributing a cost to different activities and to assessing what animals do against some optimal behaviour. Ideally, metabolic rate would be estimated directly by measuring heat output but, until recently, this has not been easily tractable with shes so instead metabolic rate is usually esti- mated using indirect methods. In the laboratory, oxygen consumption rate is the indirect method most frequently used for estimating metabolic rate, but technical requirements preclude the measurement of either heat output or oxygen consumption rate in free-ranging shes. There are other eld methods for estimating metabolic rate that can be used with mammals and birds but, again, these cannot be used with shes. Here, the use of electronic devices that record body acceleration in three dimensions (accelerometry) is considered. Accelerometry is a comparatively new telemetric method for assessing energy metabolism in animals. Correlations between dynamic body acceleration (DBA) and oxygen consumption rate demonstrate that this will be a useful proxy for estimating activity-speci c energy expenditure from shes in mesocosm or eld studies over extended periods where other methods (e.g. oxygen consumption rate) are not feasible. DBA therefore has potential as a valuable tool for attribut- ing cost to different activities. This could help in gaining a full picture of how shes make energy-based trade-offs between different levels of activity when faced with con icting or competing demands aris- ing from increased and combined environmental stressors.