Fish behaviour is a non-invasive and reliable Operational Welfare Indicator as it reflects fish responses to the environment and to routine husbandry operations. However, behavioural welfare assessment of commercial Atlantic salmon (Salmo salar) remains a challenge due to the lack of comprehensive, species-specific indicators that could describe the behavioural repertoire across life stages, throughout the aquaculture cycle. This study aims to obtain a 360-degree view inside the cage, combining 3 different acoustic technologies, to develop and assess on-site indicators of individual and group swimming behaviour in Atlantic salmon. A comprehensive overview of salmon behaviour, at both individual and group level within the cage, will support farmers in daily welfare assessment, representing a step forward real-time monitoring through acoustic systems. At a commercial aquaculture facility in northern Tasmania, three different acoustic transducers (Oculus M1200d, ES120-7C single-beam echosounder and ES38-18/200-18C combi transducer) will be deployed at the same time through a floating platform. Acoustic sampling will be conducted in four production cages, containing two salmon size classes (approximately 500 g and 5 kg). Acoustic observations will be complemented by manual fish measurements and underwater video recordings collected concurrently to validate behavioural metrics. The performance of the acoustic technologies, alone and in combination, will be compared to determine which behavioural indicators can be reliably measured using acoustics alone and whether integration with established monitoring methods, such as machine vision, is required. The study is expected to provide a set of species-specific indicators of salmon behaviour in commercial cages. The integration of Oculus video-like data with single-beam measurements is expected to achieve individual-level behavioural resolution. By identifying species-specific behavioural metrics, this research will contribute to the development of practical, on-farm welfare monitoring tools and support precision aquaculture through improved behavioural assessment and management of farmed Atlantic salmon, while gaining knowledge on the species ecology.