The boom of sonar, the roar of propellers and the whine of drills as they rip into the seabed – humans pound the ocean with noise. These alien sounds distort marine soundscapes and affect fisheries in many ways. Local catches change straight away as noise disrupts fish behaviour and communication, and in the long term, fish stocks are likely to decline. Better regulation and international cooperation are needed to dull the racket.
In an area off the Norwegian coast exposed to airgun noise from seismic exploration, catch rates of cod in long-line fisheries reduced by 55 to 80 percent. Meanwhile, bycatch of cod in trawl fisheries for saithe increased threefold. Noise from seismic surveys reduced long-line catch rates of both Greenland halibut and haddock by 16 to 25 percent but doubled gillnet catch rates for Greenland halibut and redfish.
The noisy conditions may cause fish to stop feeding and miss the long-line baits but then move into deeper water and get entangled in gillnets and bottom trawls. Catch rates may also change when human-made noise affects the predators and prey of target fish species. When Ambon damselfish were exposed to passing boat noise, they were consumed more than twice as quickly by dusky dottybacks.
