Nord Stream: Underwater Noise Levels Assessed

A study has been conducted in cooperation between Nord Stream, the Swedish Defence Research Agency (FOI) and the Swedish Nature Protection Agency, in order to establish the underwater noise levels in the sea close to the Natura 2000 area at Norra Midsjöbanken, to the south of Gotland.

Noise emanating from regular commercial maritime traffic as well as Nord Stream’s construction works has been assessed. The study was conducted from January to April this year, and the final report on the results is now available.

The report confirms that Nord Stream’s construction works caused an increase in the underwater noise levels which is comparable to that of passing commercial vessels. The construction works were carried out during a limited period of time and in a limited area. The ambient underwater noise could mainly be attributed to the vessels involved in the construction works, e.g. the pipe-lay vessel or the anchor handling tugs, and to a lesser extent from other construction related work such as trenching or placing the pipe on the seabed.

”We have been able to apply our unique competence within marine environment research in order to successfully conduct measurements in an area in the middle of the Baltic Sea. During the study, we have developed new methods of analysis for the purpose of measuring underwater noise levels as well as noise from commercial maritime shipping. We were surprised to learn about the high levels of underwater noise caused by passing vessels using the route close to this Natura 2000 area,” says Torbjörn Johansson, Researcher in underwater acoustics with the FOI.

”The scientific knowledge about the biological effects from underwater noise is in an early phase; this study however contributes new information concerning the situation in the Baltic Sea. According to the EU Marine Strategy Framework Directive one criterion for a good environmental status is underwater noise levels. Activities which cause such significant underwater noise levels that they could damage the marine eco-system should be constrained in terms of time as well as impact area, so that the noise will not cause lasting negative effects on the environment. This study provides us with a good starting point for our future work to preserve and protect the marine environment,” says Sverker Evans at the Marine and Water Management Agency (formerly working for the Nature Protection Agency).

“We are very pleased to be able to contribute to the improved knowledge concerning the underwater noise levels at Norra Midsjöbanken, a Natura 2000 area situated fairly close to a route with intense maritime traffic. At the same time, we have been able to verify the assessments from Nord Stream Environmental Study – the corner stone of our application to the Swedish government to construct the natural gas pipeline,” says Nicklas Andersson, Head of Permitting Sweden and Denmark, Nord Stream AG.

Fish and marine mammals have good hearing and they depend on sound for communication, navigation and for finding food. High ambient underwater noise levels may therefore be harmful to marine wildlife. Future developments of infrastructure at sea, as well as increased maritime shipping, therefore make it critical to increase the present limited knowledge about underwater noise levels in the seas.