This thesis investigates surface activity behaviours in juvenile Atlantic salmon reared in a recirculating aquaculture system
(RAS), examining how different feeding regimes influence surface behaviour. Enhanced understanding of Atlantic salmon
behaviour is important for both optimizing production and improving fish welfare. By observing video footage and
annotating various surface behaviours, a comprehensive dataset was established, including different behaviour types and
temporal data across multiple experimental tanks. These observations provide insight into how surface activity, such as
jumping and breaching, manifests in a tank environment seen in RAS, supporting the viability of surface activity as a welfare
indicator (WI). The feeding regimes applied in this experiment included a continuous feeding plan, representing the
commercial standard for juvenile salmon, and a meal-based feeding plan consisting of three meals per day (morning,
midday, and evening). This experimental design allowed for valuable insight into how juvenile salmon respond to different
feeding strategies. Results indicated that continuously fed salmon displayed significantly more surface activity than meal-
fed salmon. Additionally, surface activity was significantly higher during the morning feeding period regardless of feeding
regime. Furthermore, the study found that different types of behaviours, such as jumping and breaching, exhibited spatial
preferences within the tank. Overall, the findings of this thesis highlight the potential of surface activity as a practical
welfare indicator, particularly as advancements in surveillance technologies facilitate accurate behavioural monitoring.