Potential application of precision technology to monitor welfare and interactions of cage-farmed fish with wild fish species

During the recent years, the concept of sustainability in aquaculture has increased its popularity and interest in it. In this background, especially for the marine cages, the interactions between fish reared and wild fish can affect welfare and health status of both farmed and wild fish populations in the ecosystem [1]. The presence of farmed fish in cages can increase competition for food between wild and farmed fish, as they share the same marine environment. The presence of fish-eating birds and/or pelagic fish predators, as tuna and bluefish, can cause stress and damage to farmed fish populations [2,3]. Good management practices and environmental control are needed to monitor these interactions. Fish farmers are looking for reducing negative impacts through cage placement, waste management and fish welfare monitoring. In this scenario, this study is performed to evaluate growth performance and welfare status of reared fish in offshore cages and the possible interactions with wild fish, observed in aggregation near the cages. For the aim of the study, a non-invasive device, a precision technology system of video cameras and water quality sensors, is employed in an offshore cage aquaculture plant, located in the Gulf of Manfredonia (Puglia region), specialized in gilthead sea bream (Sparus aurata) and European sea bass (Dicentrarchus labrax) farming, according to the IMTA (Integrated Multi-Trophic Aquaculture) system. This precision technology system is installed thanks to FishVision research project, supported by Agritech. This grant is equipping two farming cages (1/sea bream and 1/sea bass). The video monitoring consists in three cameras positioned inside the cage. Two stereoscopic cameras are synchronized for 3D analysis and another camera is placed in the opposite direction of the others, towards the outside of the net cage (Figure 1). The video streams are 10 sec long and with 3 frames; consequently, they are stored in in HEVC (high-efficiency video encoding) files format, to be sent via network to a repository. A thermal camera is pointed towards the farm area to record marine currents. Water quality is monitored by means of sensors to determine the most important physico-chemical parameters. A platform connected to the repository is created to collect data. Zootechnical performances and histological liver status are evaluated to show physio-pathological patterns and behaviour of farmed fish in presence of wild fish, in relation to farming technique and water quality trend. Based on this study, precision digital system allows to monitor the behaviour of reared fish in presence of wild fish and helps the fish farmers to predict the measures to take in order to manage this problematic interaction.