Just how much shipping noise are harbour porpoises exposed to — and how does it affect their behaviour? In a new paper, SATURN researcher Caitlin Frankish and colleagues found that porpoises were exposed to ship noise above ambient 1/3 of the time, and that ships as far away as 2 kilometres caused animals to react.
The animation below shows just how much shipping noise a single harbour porpoise is exposed to in the Kattegat.
Below, the left animation shows evidence that at short spatial and temporal scales, the harbour porpoises exhibited horizontal avoidance behaviours (i.e. the animal moved away from the vessel). On the right, the animation shows a vessel passing over a harbour porpoise from above. The colour illustrates the depth that the animal dived to: when the ship is directly overhead, the animal here dove to more than 60m deep.
Over many exposure events, the energetic costs of reactions to vessel noise could accumulate. Stay tuned to hear how we incorporate these findings into an agent-based model (http://depons.eu) to investigate potential population-level effects!