Intelligent smart device for tracking fish behaviour

With the use of electronic tracking technology, data on fish movements, physiology and environmental parameters can be collected from each tagged individual. The perfect tag - small size, lasting activity, long distance data transmission (e.g. radiotransmitters, acoustic transmitters, pop-up satellite archival tags) - does not exist, and the choice of telemetry technology and tagging method (external, intracelomic, intragastric) depends on fish species, life stage and research question. The proposed solution within the AQUAEXCEL2020 EU project is a stand-alone, small and light (1 g) device (AEFishBIT), composed of a tri-axial accelerometer, a microprocessor, a battery and an RFID tag for quick-smart identification. The device is externally attached to the operculum to monitor physical activity by mapping accelerations in x- and y-axes, while operculum beats (z-axis) serve as a measurement of respiratory frequency. Initial functional validation has been made with gilthead sea bream and European sea bass juveniles in swimming test chambers, highlighting a high correlation of oxygen consumption and swimming activity with the calculated AEFishBIT records (MartosSitcha et al., 2019; Frontiers in Physiology 10:667). Current studies with free-swimming fish reveal that the attachment protocol does not have a negative impact on growth performance in active feeding fish, offering a wide range of new information based on individual behaviour: i) the switch from nocturnal to diurnal rhythms of activity across season, ii) the different energy partitioning for growth and maintenance, iii) the asynchrony of movements as an indirect measure of aging and adaptability to culture environment, and iv) the different coping behaviour of fish challenged with low water oxygen concentrations. AEFishBIT also provides reliable information of disease outcome in fish parasitized with the intestinal myxozoan Enteromyxum leei, emerging as the ideal complement for sensing the quality of the enviro