Precision fish farming: A sensor-based study on Dicentrarchus labrax in a sea cage environment

The remote real-time monitoring of farmed fish health and welfare without disrupting daily management practices is crucial for the aquaculture industry. This study evaluated the effectiveness of wireless environmental and biological sensors in monitoring fish welfare and gathering insights into potential predictors of mortality and growth of European sea bass (Dicentrarchus labrax). Environmental sensors were deployed within a net pen and eight fish were implanted with pressure and accelerometer sensors to compute acceleration and depth of individual fish. All sensors were connected to a central Hub, enabling real-time visibility for fish farmers, and monitoring was carried out over 68 days. Significant positive correlations were observed between growth and temperature, as well as between growth and dissolved oxygen levels. However, no significant correlations were found between mortality data and any of the parameters considered (environmental, feed load or fish-related traits). Our findings also revealed that fish depth and acceleration, which serves as a proxy for energy expenditure, were sensitive to environmental fluctuations. Fish exhibited a circadian rhythm in both depth and swimming activity, with higher activity in deeper waters during the daytime and lower swimming activity in shallower waters during the night. Temperature, dissolved oxygen, and the amount of feed distributed also influenced fish swimming activity and depth. This study demonstrates that acoustic telemetry, by leveraging biological and environmental data collected via wireless sensors, is a suitable tool to monitor fish directly in sea cages, as well as environmental variations. We also provide initial insights into the potential of predicting the growth performance of European sea bass. Analyses presented here are preliminary and require further refinement, including longer-term observations spanning at least an entire year and the incorporation of additional parameters (e.g. turbidity, water currents). Additionally, a replicability check of the study is necessary, incorporating more cages and other fish farms.