Anthropogenic sources increasingly contribute to the underwater soundscape and this may negatively impact aquatic life, including fish. Anthropogenic sound may mask relevant sound, alter behaviour, physiology, and may lead to physical injury. Behavioural effect studies are often seen as critical to evaluate individual and population-level impact. However, behavioural responsiveness likely depends on context and characteristics of sound stimuli. We pose that ambient sound levels, signal-to-noise ratio (SNR), and pulse rate interval (PRI), could affect the behavioural response of fish. To study this, we experimentally exposed groups of tagged European seabass (Dicentrarchus labrax) to different impulsive sound treatments that varied in pulse level, elevated background level, SNR, and PRI. Upon sound exposure, the seabass increased their swimming depth. The variation in the increase in swimming depth could not be attributed to pulse level, background level, SNR or PRI. It may be that the current range of sound levels or PRIs was too narrow to find such effects.
- Signal-to-noise ratio and pulse rate interval may be important for the behavioural responses of animals to sound exposures.
- Seabass increased swimming depth upon sound exposure, but did not change their speed, group cohesion and spatial avoidance.
- The increase in depth was dependent on pre-exposure depth and not on signal-to-noise ratio and pulse rate interval.
- A qualitative overview of five sound exposure studies on seabass with similar before-during-after design is provided.