Fig 1.
The map shows precise close up location of the farm and study cage with 5 m depth contours as well as zoomed out maps of general location in relation to surrounding islands with 10 m depth contours. Map reprinted from kort.foroyakort.fo under a CC BY license, with permission from the Faroese Environment Agency, Umhv∅rvisstovan. Original copyright 2022.
Table 1.
Equipment deployed.
Fig 2.
Aerial and side on view of the study cage with the location of echo sounders (yellow circles and cones show viewing area of echo sounders), pressure sensors (attached to the net and shown as blue bars) and video cameras (shown as circles or cones depending on viewing angle). Camera viewing angles are approximate. The camera with diagonal stripes is the feed camera, which was nearer the surface than the bottom mounted cameras.
Table 2.
Operational welfare scores recorded.
Fig 3.
Current and wave directions from two current profilers.
Wind roses of the currents and waves measured by the two profilers. Currents are towards the indicated directions, waves travel from the indicated directions.
Fig 4.
Wave height measured by two current profilers.
The wave heights measured throughout the monitoring period. The Sentinel V was located south of the study cage whereas the AWAC was located north of the farm.
Fig 5.
Depth measured by pressure sensors.
Depth measured by pressure sensors located at the bottom of the side net (Side- west, south, east, and north) and half way from the side to the centre (Bottom- west, south, east, and north). Points are depths measured and lines are lines of best fit. Darker points and lines are depths in southbound current and light points and lines are depths in northbound current.
Fig 6.
Proportion of time spent by the majority of the salmon in frame standing on current.
Points are proportion of time where the salmon were standing on current in a video. Lines represent model predictions of the probability of a video having salmon standing on current a majority of the time. Model predictors are current speed and direction. Lighter colour signifies a northbound current direction whereas a darker colour signifies a southbound current direction.
Fig 7.
Swimming effort measured in tail beats per second (tbps) over current.
Swimming effort in salmon standing on current in northbound and southbound currents. Shading indicates wave length less than 12 seconds (lighter colour) and more than 12 seconds (darker colour).
Fig 8.
Proportion of time per video where “Many” (top panel) or “Any” (bottom panel) salmon were recorded.
Light boxes indicate small waves and dark boxes indicate large waves. Dots are raw data and boxes and whiskers represent quartiles. Wave height was split at 1.1 m with “Small” waves being up to and including 1.1 m tall and “Large” waves being taller than 1.1 m. This was an approximate 50/50 split of the available data, and does not necessarily represent biological significance. Statistics are carried out using continuous wave parameters.
Fig 9.
Number of net collisions per 300 seconds over wave height split by current speed.
Dots are number of collisions normalised to per 300 seconds of video containing salmon over measured wave height. Lines are best lines of fit using a poisson fit. Current was split at 0.2 m s-1 with light dots and lines representing currents up to and including 0.2 m s-1 and dark lines and dots representing currents stronger than 0.2 m s-1.
Fig 10.
Depth and dispersal of fish seen in the south echo sounder over hour in the day when current is weak.
Back scatter strength (Sv) indicates fish density, with higher values (-70) indicating many fish and lower values (-100) indicating fewer fish. Data presenting current stronger than 0.11 m s-1 is not included for simplicity.
Fig 11.
Depth and dispersal of fish over current.
The upper and lower panels indicate the two echo sounders, and the left and right panels the direction of current. Back scatter strength (Sv) indicates fish density, with higher values (-70) indicating many fish and lower values (-100) indicating fewer fish. Data presenting shoal depth during the night is not included for simplicity.
Fig 12.
Depth and dispersal of fish over wave height (Hm0) in weak current.
The left and right panels are the south and north echo sounder. Data where current exceeded 0.11 m s-1 are excluded. Signal strength (Sv) indicates fish density with higher values (-70) indicating many fish and lower values (-100) indicating fewer fish. Data presenting shoal depth during the day not included for simplicity.
Fig 13.
Distribution of welfare scores over time.
Proportion of salmon with summed welfare scores between 0 and 9. A score of zero indicates that the fish had no injury at all and higher scores are more injuries.