Noise in the Mediterranean Sea

Noise-Hotspots in the Mediterranean Sea

It is very loud in the Mediterranean Sea – and, to make matters worse, it is very loud in important habitats of endangered marine animals. This is the conclusion reached by scientists from France, Italy, Switzerland and the USA who – for the first time – presented a basin-wide map that shows the density of the main anthropogenic noise sources in the Mediterranean Sea. The report “Overview of the Noise Hotspots in the ACCOBAMS Area, Part I – Mediterranean Sea”, co-authored by Silvia Frey of OceanCare, is drawn from a dataset covering 1,446 harbours and marinas, 228 oil drilling platforms, 830 seismic explorations, 7 million ship positions, 52 wind farm projects, as well as publicly available information regarding military activities for the period 2005 to 2015.

The scientists found that at any given time around 1,500 vessels on average are in transit in the Mediterranean – not taking into account the numerous leisure crafts. The increase in seismic activities, especially for oil and gas exploration, is particularly striking. While in 2005 airgun use, sending loud impulsive noise of up to 260 decibels towards the sea floor, affected 3.8% of the Mediterranean’s surface, this share increased to 27% in 2013. Another significant noise contributor is military noise. Yet, data on military manoeuvres deploying medium and low frequency sonar are generally not available to the public. This means that the findings in the report must be seen as minimum values, or, in other words, an underestimation of the reality of the situation.

The report’s mapping, for the first time, reveals that noise hotspots overlap with protected areas and/or with areas that are of particular importance to noise-sensitive marine mammal species. These include the Pelagos Marine Mammal Sanctuary in the Ligurian Sea, the Strait of Sicily, parts of the Hellenic Trench, as well as the waters between the Balearic Islands and continental Spain where noise-producing activities accumulate.

The report was commissioned by the Agreement on the Conservation of Cetaceans in the Black Sea, Mediterranean Sea and Contiguous Atlantic Area (ACCOBAMS)  to identify areas of concern, to propose the need for further scientific assessment, and to use as a foundation to develop appropriate conservation measures.