Abstract
Simple SummaryAssessment of the energetic costs of different living activities is of primary interest among fish biologists. However, assessing energy expenditure in free-swimming fish is challenging owing to the difficulty of performing such measurements in the field. Therefore, the use of implant fish with sensors that transmit signals that serve as a proxy for energy expenditure is a promising method to counter these limitations, allowing remote monitoring in tagged fish. The aim of this study was to correlate the acceleration recorded by the tag with the activities of the red and white muscles and the oxygen consumption rate (MO2), which could serve as a proxy for energy expenditure, in gilthead sea bream (Sparus aurata), a key species in European marine aquaculture. The acceleration recorded by the tag was successfully correlated with MO2. Additionally, through electromyographic analyses, we determined the activities of the red and white muscles, which are indicative of the contributions of aerobic and anaerobic metabolisms during swimming. Finally, the tag implantation did not affect the swimming performance, metabolic traits, and swimming efficiency of the sea bream. By obtaining insights into both aerobic and anaerobic metabolisms, sensor mapping with physiological indicators may be useful for the purposes of aquaculture health/welfare remote monitoring of gilthead sea bream.Measurement of metabolic rates provides a valuable proxy for the energetic costs of different living activities. However, such measurements are not easy to perform in free-swimming fish. Therefore, mapping acceleration from accelerometer tags with oxygen consumption rates (MO2) is a promising method to counter these limitations and could represent a tool for remotely estimating MO2 in aquaculture environments. In this study, we monitored the swimming performance and MO2 of 79 gilthead sea bream (Sparus aurata; weight range, 219–971 g) during a critical swimming test. Among all the fish challenged, 27 were implanted with electromyography (EMG) electrodes, and 27 were implanted with accelerometer tags to monitor the activation pattern of the red/white muscles during swimming. Additionally, we correlated the acceleration recorded by the tag with the MO2. Overall, we found no significant differences in swimming performance, metabolic traits, and swimming efficiency between the tagged and untagged fish. The acceleration recorded by the tag was successfully correlated with MO2. Additionally, through EMG analyses, we determined the activities of the red and white muscles, which are indicative of the contributions of aerobic and anaerobic metabolisms until reaching critical swimming speed. By obtaining insights into both aerobic and anaerobic metabolisms, sensor mapping with physiological data may be useful for the purposes of aquaculture health/welfare remote monitoring of the gilthead sea bream, a key species in European marine aquaculture.
Highlights
Measurement of metabolic rates in animals, including fish, is of primary interest because it provides a valuable proxy for the activity-dependent energetic costs of different living activities [1,2,3]
The fish implanted with EMG wires were excluded from the analysis of the link of swimming performance and mass to MO2 during the trial and estimation of the metabolic rates of sea bream
For both the absolute and relative Ucrit values, the performances negatively correlated with the fish mass regardless of the tagging condition (p < 0.001 for both absolute and relative Ucrit; Figure S4); larger sea bream displayed lower swimming performances
Summary
Measurement of metabolic rates in animals, including fish, is of primary interest because it provides a valuable proxy for the activity-dependent energetic costs of different living activities [1,2,3]. The SMR represents the minimum amount of oxygen needed by fish to support their aerobic metabolic rate [2]. MMR refers to the maximum rate of aerobic metabolism of an animal and is, associated with the maximum rate at which oxygen can be transported from the environment to tissue mitochondria [3]. These two metabolic traits are measured during a critical swimming test (Ucrit). The SMR can be estimated on the basis of the relationship between oxygen consumption rate (MO2) and swimming speed, extrapolating the value at the speed of zero. The numerical difference between MMR and SMR describes the absolute AS, which quantifies the amount of oxygen that can be consumed to support all physiological and locomotive activities, such as migration, feeding, or reproduction [4,5]
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