Monitoring water temperature during the growth of gilthead sea bream juveniles in sea cage aquaculture

Mediterranean Sea is showing an increase in water temperature with effects on mariculture cage systems especially on growth of euryhaline fish species altering feeding behaviour and causing physiological stress. Gilthead sea bream is able to tolerate a moderate increase in temperature and feeding regimes need to be reduced. Innovations in digital systems applied to the record temperature trend and water quality can help mitigate risks on the environment and improve farm management. In this context, a study was conducted to investigate the application of a digital water monitoring system in a sea cage farm in the South Adriatic Sea. The study aimed to analyse the mean body weight and growth trend of gilthead sea bream (initial mean body weight: 12.75 g) in relation to water temperature, from mid-June 2024 to mid-December 2024. A digital water monitoring system was installed in a cage equipped with a water temperature sensor to record this parameter in real time and store the data in the cloud. The mean body weight was sampled monthly and compared to that of sea bream juveniles (initial mean body weight: 12.1 g) reared in a cage at the same stocking density during a previous production cycle in the same fish farm (2022). During that earlier cycle, water temperature was only recorded occasionally. The growth model of the two productive cycles were studied and data were submitted to unpaired t-test statistical analysis using GraphPad Prism 10.4.0 (621). In the summer of 2024, sea bream had a mean body weight that was 23% lower than those reared in the same season in 2022, when water temperatures had higher average values (>29 °C) for a prolonged time than those recorded in 2022 (26 °C). Thanks to real-time water temperature monitoring, fish growth was recovered by adjusting the feeding rate more accurately. As a result, after six months, no significant differences were observed between the mean body weight recorded in 2022 (119.8±3.38 g) and in 2024 (121.3±2.07 g). This trial demonstrated that the application of a digital system for water temperature monitoring improved the feeding strategy and the fish growth also with benefits for the environment. This research was supported by PNRR NEXTGENERATIONEU, Agritech [CN00000022], Spoke 5, linea C, sottotematica 2, UNIVERSITÀ DEGLI STUDI DELLA TUSCIA, FishVision Project (CUP J83C22000830005).