Laboratory protocol to calibrate sea lamprey (<Emphasis Type="Italic">Petromyzon marinus</Emphasis> L.) EMG signal output with swimming |
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Authors: | P R Almeida I Póvoa B R Quintella |
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Institution: | (1) Department of Biology, University of évora, 7002-554 Evora, Portugal;(2) Institute of Oceanography, Faculty of Sciences of the University of Lisbon, Campo Grande, 1749-016 Lisboa, Portugal |
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Abstract: | A correct application of electromyogram (EMG) telemetry in the field can be a powerful tool to evaluate activity patterns
and swimming strategies of fishes. We evaluated the swim performance of seven untagged sea lampreys (Petromyzon marinus L.) with critical swim speed (U
crit) tests. The average U
crit observed was c. 1.03 ms−1 (i.e., 1.14 BL s−1). The strongest reotaxic response was observed during tests using water velocities between 0.4 ms−1 and 0.8 ms−1. During two consecutive years (i.e., 2004 and 2005), in order to model upstream migration of sea lampreys with CEMG transmitters
(Lotek Wireless), we calibrated EMG signal with swim speed. A high correlation between EMG records and swim speed was observed
in both years (r
2 = 0.74–0.93). However, in spite of methodology improvements and standardization in the second year of study, differences
in intercepts and slopes were observed between individuals, making the determination of a unique calibration equation for
all tagged animals unfeasible. Therefore, it appears to be necessary to obtain the relationship between EMG signals and swimming
speed for each lamprey using laboratory procedures, prior to release in the wild. It is unknown whether this variability results
from individual locomotor behaviour, physiological state and/or variation in placement and functioning of the EMG transmitters.
The results of five laboratory calibrated lampreys, released in the River Mondego, revealed considerable differences between
swim speeds calculated with EMG signal (calibration equation) and ground speed therefore it was not possible to successfully
calibrate the EMG signal output with swimming speed. In order to accomplish this, longer continuous swimming tests in laboratory
are necessary. Nevertheless, the calibrated swimming effort gives reliable information about the swimming behaviour and permits
comparison of the results between animals. |
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Keywords: | Electromyogram CEMG transmitters Biotelemetry Calibration Critical swimming speed |
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