Assessing effects of increased noise levels on fish behaviour

Abstract

Man-made noise can affect physiology and behaviour of animals of all taxa, including fish. However, there is not much known about effects of increased noise levels on anti-predator and foraging behaviour, which are both essential for survival and reproduction. In our laboratory study, we investigated effects of increased noise levels on these behaviours in two sympatric fish species, three-spined sticklebacks (Gasterosteus aculeatus) and European minnows (Phoxinus phoxinus), which differ in their anti-predator defences and likely in their hearing capabilities. Our study indicated that both behavioural contexts were affected by increased noise levels, but effects differed between species. Sticklebacks responded to a visual predatory stimulus sooner when exposed to additional noise playbacks than in control conditions, whereas minnows were not affected by the noise treatments. In foraging experiments, both fish species consumed fewer water fleas, but the reasons fish decreased food consumption seemed species specific: sticklebacks increased the number of foraging errors, whereas minnows tended to decrease their foraging effort by interacting socially more often and more individuals were inactive during increased noise level conditions. To allow for controlled comparative experiments, our studies were conducted in the laboratory. Complementary field experiments ensuring natural acoustic conditions will be necessary to investigate whether species differences can translate into community effects and whether these effects differ between different kinds of noise, such as drilling, pile driving and energy device operation noise. Expanding research to commercially important fish and quantification of particle motion in addition to sound pressure as most fish, and likely invertebrate species, perceive particle motion rather than sound pressure, would further deliver valuable knowledge for industry, policy makers and fisheries managers about how marine renewable energy devices may interfere with the marine environment.