Physiological Telemetry in Fisheries Research

For over 50 years, radio and ultrasonic telemetry devices have been implanted in or attached to fish to document their distribution and movement. More recently, telemetry devices have been developed that use external sensors to provide information (e.g., depth, water temperature, pH, salinity) on the environment that fish are inhabiting. The ability to measure these environmental variables is important for understanding habitat use and preferences; however, they provide little information on how or why these fish respond as they do, either behaviorally or physiologically, to their environment.

Interest in exploring the energetic consequences and mechanistic basis of fish distribution and movement has fueled the rapid development of a variety of physiological telemetry devices (e.g., those that measure locomotory activity or heart rate) that are proving to be useful for basic and applied fisheries research. The largest benefits from physiological telemetry arise from the ability to continuously monitor behavioral and/or physiological attributes of free-swimming fish. Thus, we can release fish into natural environments and monitor their response to different stressors in situ and in real time. In this article, we review the broad range of applications for which we have utilized physiological telemetry devices to answer pressing fisheries questions.

One of the applied research areas that has benefited from physiological telemetry is the assessment of the true impacts of catch-and-release angling. Using locomotory activity transmitters, we have monitored the response of nesting male largemouth bass to angling, and have documented an impairment in their ability to provide parental care following this disturbance. We have also used activity transmitters to assess the effects of live-well density on the behavior of smallmouth bass. More recently, we have also begun field testing heart rate telemetry devices and have successfully monitored cardiac activity before, during, and after angling (Fig. 1). This approach to assessing the impacts of catch-and-release angling will permit the identification of those practices that are detrimental to fish and will provide much needed information on the sublethal effects of different angling and handling practices. A key focus area for future research is a comparative study of how various sportfish species that often are released--both freshwater (e.g., muskellunge and trout) and saltwater (e.g., bonefish and tarpon)--respond to angling stress.

Knowledge of the activity and metabolic rates of fish is also important in the development and application of bioenergetics models for managing fisheries. Physiological telemetry has permitted the refinement of energetics models by providing empirical data on the inherently difficult-to-monitor respiration components of the models. Using forced swimming trials in a respirometer, relationships can be developed between different telemetered data (e.g., locomotory activity or heart rate) and both swimming speed and oxygen consumption (Fig. 2). These calibrations can be used to estimate the metabolic rates of free-swimming fish in the field (i.e., estimating oxygen consumption from changes in heart rate or locomotory activity). Furthermore, we can use the relationship between locomotory activity and swimming speed to estimate the distance traveled by individual fish. Using this approach, we have determined that for smallmouth bass, significant energy can be expended undertaking fine-scale, localized movements, a finding that would be undetectable using conventional locational telemetry. We have also examined the physical activity associated with largemouth bass spawning, quantified and compared the energetic cost of parental care activity of male smallmouth bass and largemouth bass, and we are in the process of developing gender-specific seasonal energetics budgets for both of these species.

In addition to the uses described here, physiological telemetry is also an effective tool for studying migration energetics, determining areas of difficulty associated with the use of fish passage devices, assessing fish responses to thermal stress (i.e., winter ecology, thermal effluents), and in developing welfare correlates in aquaculture operations. We feel that the continued development and refinement of physiological telemetry devices will facilitate the collection of information that would otherwise be unattainable. For example, by merging the use of physiological telemetry with molecular genetic techniques, we hope to assess how evolutionary divergence over time translates into the meaningful biological differences that serve as the basis for adaptation and ultimately, speciation.

Steven J. Cooke, David H. Wahl, and David P. Philipp, Center for Aquatic Ecology<p> Please report any problems with or suggestions about this page to:
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