A Novel Miniaturized Biosensor for Monitoring Atlantic Salmon Swimming Activity and Respiratory Frequency

Abstract

The advanced development of sensor technologies has led to the emergence of fish biosensors that are currently used for research and commercial purposes. AEFishBIT is a miniaturized biosensor attached to fish operculum that measures physical activity and respiration frequencies. In this study, we determined the effect of the tagging method and evaluated the use of this biosensor to monitor post-smolt Atlantic salmon in a tank-based system. The use of piercing fish tag had a negative impact on the gills and operculum, unlike the identical protocols used in gilthead sea bream and European sea bass. In contrast, a surgical thread did not show any apparent tissue damage. Two data recording schedules were considered to monitor immediate early reaction to fish handling and light regime changes (records every 15 min over 2 days) or adaptation to new light conditions (records every 30 min over 4 days). Data showed stabilization of physical activity 8 h post-tagging, with different steady states for the activity/respiratory ratio after changes in light intensity that reflected a different time course adaptation to new light conditions. High correlations were observed between AEFishBIT and video recording data. These findings supported the use of AEFishBIT as a promising tool for smart sensing of Atlantic salmon.

Revising the Impact and Prospects of Activity and Ventilation Rate Bio-Loggers for Tracking Welfare and Fish-Environment Interactions in Salmonids and Mediterranean Farmed Fish

“…For instance, in a common garden system with all fish under identical environmental conditions in the same experimental tank, respiratory rates are negatively or positively correlated with body mass in gilthead sea bream juveniles having slow-and fast-growing phenotypes, respectively (Perera et al, 2021a). This feature highlighted a higher contribution of energy to growth in fast growing fish, which was also evidenced when AEFishBIT comparisons were made between salmon and gilthead sea bream (Kolarevic et al, 2021). Likewise, measurements of respiratory rates in gilthead sea bream varied with growth changes across season and development, while changes in locomotor activity appeared less variable (Figure 6A), a feature that reinforces the concept of AEFishBIT respiratory frequency as an indirect measure of basal metabolism and hence growth potentiality among fish species and studies.…”

“…Thus, alternative surgery approaches were developed for trout and salmon (400-500 g onward), using a flexible heat shrink polyethylene tube ring sutured on the operculum and with AEFishBIT held in this ring. This tagging method led to 100% retention rate (7 days post-tagging) with no significant tissue lesions or gill lamellae necrosis in salmon of 400-600 g body weight (Kolarevic et al, 2021). This procedure still provoked some tissue damages in trout, though it can be prevented by means of a suture step at operculum 2 weeks before the implantation of the heat shrink polyethylene ring with the AEFishBIT device.…”

“…As part of the validation procedure, fish species differences (gilthead sea bream vs. European sea bass) in the amplitude and frequency of operculum and body tail movements were also evidenced using recorded raw data from exercised fish, which highlighted the anatomical and metabolic adaptive features of European sea bass as a fast swimming predator (Ferrer et al, 2020). Additionally, in Atlantic salmon, good correlations between AEFishBIT and video recording data have been provided by Kolarevic et al (2021), providing additional evidence for a reliable use of AEFishBIT as a smart tool for sensing farmed fish of high economic value for aquaculture. The tracking of these validation/calibration procedures is summarized in Figure 1.…”

“…Certainly, locomotor and feeding rhythms are of endogenous origin, as they can persist under constant conditions without external time cues (Madrid et al, 2001;Sánchez-Vázquez and Madrid, 2001). However, it is also known that vertebrate animals in polar regions show highly diverse activity patterns ranging from entrained circadian rhythms to arrhythmicity patterns (Cockrem, 1990;Ashley et al, 2012), as reported for AEFishBIT measurements of locomotor activity and respiratory rates in Atlantic salmon under continuous light regimes and hourly access to food excess (Kolarevic et al, 2021).…”

“…In other words, the ratio between respiratory frequency and physical activity values can be considered as a metabolic index whose variations can be indicative of differences in the energy partitioning. Indeed, the variations of this metabolic index have been proven useful to assess the adaptation of salmon to different light regimes (Figure 6B; Kolarevic et al, 2021). How this knowledge can be used to define new algorithms based on the combination of physical activity and respiratory frequency as integrative welfare indicators is underway to better dissociate the growth changes related to development, natural environmental cues, and aquaculture stressors, with an impact among other factors on the optimization of water quality and available space for the interaction of individuals with the environment and their congeners.…”