Response of Atlantic salmon in flexible sea cages to waves and currents: Measurements at farm-level and modeling

The shift towards salmon farming in more exposed locations has been an industry-wide trend for the last decade. Moving fish farms to locations with high water currents and waves can improve production by providing more stable temperatures and water quality, as well as reducing the negative environmental impacts of fish farming. This study investigates how waves affect the behavior of salmon from the same group, reared at different locations within a fish farm in standard circular sea cages. Using echosounders, DO (dissolved oxygen), temperature sensors and ADCP (Acoustic Doppler Current Profiler), we show that salmon avoid waves, swim below them and maintain their normal behavior. We also show that salmon behavior is related to the exposure of the cage, in the farm layout, to waves and currents. An integrated numerical model of fish and flexible sea cages is used to simulate the fish behavior under waves and currents and it able to reproduce the observed fish distributions in general.