Attachment, validation, and preliminary deployment of ultrasonic heart rate transmitters on largemouth bass, Micropterus salmoides

Abstract

Although there are numerous published accounts of studies utilizing heart rate ( fH) transmitters in fish, few of these studies provide sufficient detail to aid other researchers in deploying these devices. Here, we detail the attachment, validation, and preliminary deployment of a commercially available ultrasonic fH transmitter. We used largemouth bass, Micropterus salmoides, for this study because they principally modulate cardiac output using fH, making them logical candidates for this technology. Using an external harness that balanced the battery on one side of the dorsum, and the transmitter on the other, we attached the device to 13 fish. Electrodes were positioned ventral-laterally to the pericardial cavity. Doppler flow probes were used to validate that the transmitter was detecting and emitting a signal when triggered by the depolarization of the ventricle (QRS wave), as indicated by peaks in blood flow. We then deployed the fH transmitters for periods of up to 32 days, generating one of the most complete series of fH data available. We present preliminary data illustrating the information available from fH transmitters at different temporal resolutions (real time vs. hourly means), including relationship of fH to temperature, behavioral correlates of fH, and diel patterns of fH.