As an element of the cooperation between Nord Stream, FOI and the Swedish Environmental Protection Agency, measurements have been made of the underwater noise levels close to the Natura 2000 area of Northern Midsjöbanken, south of the island of Gotland.
Fish and marine mammals in the area, for example cod, herring, eelpout and seals, need to be able to communicate with one another. This they do via sound and hearing. Midsjöbanken is a protected spawning area for fish and is situated close to a busy shipping lane.
“The high levels of noise from shipping in the area were a result that we had not expected,” says Torbjörn Johansson, a scientist specialising in underwater acoustics.
It is shipping, and not actually the work on Nord Stream’s natural gas pipeline, that generates the most noise. But the vessels used in the construction work generated the same level of noise as a merchant ship.
FOI possesses unique competence in research in an ocean environment. In this project, FOI’s scientists have developed new analytical methods specially adapted for underwater noise and the sounds generated by commercial shipping.
In the EU project BIAS, FOI will be conducting further work on charting the noise levels in the Baltic by means of making further measurements of noise below the sea surface.
“Now we want to study how much noise is generated in the waters surrounding a shipping lane and how far this noise is propagated. It will be interesting to have a closer look at this,” says Torbjörn Johansson.