Researchers call for restrictions on small vessel noise
A new study has found that small vessels create more noise pollution than container ships and its authors are calling for regulations to address the problem.
Researchers at the universities of Haifa, in Israel, and Zagreb, in Croatia, found that underwater noise emissions from vessels such as motorboats, ferries and yachts were comparable to those of large commercial vessels.
Published in Scientific Data, which is part of the Nature group of publications, the study also claims that URN (underwater radiated noise) has been doubling in intensity every 10 years, and that the phenomenon results in blunt tissue trama ‘comparable to blast injuries’ on fish, crustaceans and cetaceans (such as dolphins and whales).
Marine animals exhibit stress; the noise can mask their own communication sounds; and their are risks of collision with vessels because of the interference in navigation.
The researchers created a database, the largest of its kind, they say, to catalogue video and acoustic recordings of more than 1,200 vessels in the Adriatic Sea.
“Our findings show that under certain conditions, small vessels can emit significant underwater noise pollution that influences the behaviour of marine animals, including marine mammals, fish, and invertebrates,” said study author Roee Diamant from University of Haifa’s Charney School of Marine Sciences.
“The International Maritime Organization issued regulations to reduce underwater noise from large ships and some countries have placed limits on the permittable speed of commercial vessels in coastal areas that are home to marine animals,” said Mark Shipton, a doctoral student in the Department of Marine Technologies at University of Haifa, who was responsible for undertaking the acoustic analyses in the study.
“However, there are no current regulations that address smaller vessels. In fact, the impact of noise from small vessels may be greater than those of large commercial vessels as smaller vessels cruise in coastal waters, where most marine life is concentrated.”
Data was collected with an optical camera and an acoustic recorder to capture video recordings of small vessels passing through the channel. A dedicated machine learning system, developed as part of the study, was used to identify the vessels and estimate their type, size, and speed.
For accuracy, the researchers positioned the acoustic recorder in the centre of the channel, at a depth of about 30 meters, enabling them to match each vessel identified in the video footage to the acoustic signal it created while passing through the channel.
“As we expected, the results of our analysis showed a strong correlation between the speed of the vessel and the underwater noise it emits,” said Dimant. “This could serve as a basis for developing regulation to reduce noise from small vessels, such as by imposing speed restrictions when cruising in proximity to marine protected areas or including noise monitoring in the various biological monitoring activities already undertaken at sea.”
