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Source: Federal Ministry for the Environment, Nature Conservation, Building and Nuclear Safety The BfN has published a report that describes the effects of the demolitions of sea mines from World War II in the “Fehmarnbelt” nature reserve in the Baltic Sea in August 2019 on porpoises.

Expert opinion by the Federal Agency for Nature Conservation shows that harbor porpoises are at risk from explosions in the sea

The Federal Agency for Nature Conservation has published a report describing the effects of the demolition of sea mines from World War II in the “Fehmarnbelt” nature reserve in the Baltic Sea in August 2019 on porpoises. The results show that the strictly protected harbor porpoises were exposed to a high risk of injury from the pressure waves of the blasting. In order to avoid such a hazard in the future, the Federal Ministries for the Environment, Defense and Transport set up a joint working group headed by the Federal Agency for Nature Conservation Completed exercise, after consultation with the responsible waterways and shipping authority in the nature reserve “Fehmarnbelt” in the Baltic Sea, 42 British sea mines from World War II blown up. The demolition made it possible to avert danger to life and health in a busy waterway. To this end, the German Navy had carried out its usual deterrent measures in the run-up to the blasting of the mines. After the blasting became public, the question arose whether there was a connection between the blasting and harbor porpoises stranded dead. The Federal Agency for Nature Conservation then carried out or commissioned three investigations: firstly, evaluation of measurements of the sound levels in the Fehmarnbelt nature reserve at the time of the blasting; secondly, evaluation of measurements of harbor porpoise echolocation sounds around the area at the time of the blasting with the help of so-called click detectors; and thirdly, autopsies of some of the porpoises found dead from the end of August by the University of Veterinary Medicine Hannover to investigate the causes of death. The results of the investigations show that porpoises were in the Fehmarnbelt protected area at the time of the blasting. They also show that the sound pressure of the blasting was so high in almost the entire reserve that harbor porpoises could be injured or killed. Dead harbor porpoises are found on German seashores year round. In the period from the end of August to the end of November 2019, the number of dead animals found on the Schleswig-Holstein Baltic Sea coast was 41 animals, slightly higher than the average in previous years. Not all animals were in a condition that allowed an autopsy. A third of the 24 examined animals showed injuries in the area of ​​the hearing organs, which are caused by extremely loud impulse sound events – usually explosions – and which with a high probability led to the death of the animals. However, due to the extended investigation period, the dead finds with acoustic trauma cannot be clearly traced back to the mine blasting at the end of August. Other extremely loud impulse noise events – however, these are usually blasts – can also be a possible cause Federal Agency for Nature Conservation, in which the coastal federal states are also represented. In order to improve the protection of harbor porpoises, the working group is to develop joint guidelines on nature conservation and technical requirements for the removal of old ammunition in the North Sea and the Baltic Sea. Before removing old ammunition, it is always checked whether other measures can prevent detonation in the water for example by taking them to shallow water or on land for defusing or blasting However, this is not always possible. With some contaminated sites there is an immediate danger of an uncontrolled explosion due to the critical condition of the mines or the detonation heads, such as the mines that were blown up in August 2019. If blasting is unavoidable in such cases, these are controlled and implemented with appropriate mitigation measures to protect marine species and habitats. The aim is to reduce the effects to a minimum. In order to keep the effects on the environment as low as possible, the working group that has been set up is investigating appropriate options for these cases. On the one hand, there are requirements to only carry out blasting outside of times when porpoises are breeding or raising their young. Technical solutions are also being considered to mitigate the consequences. For example, the use of so-called bubble curtains can reduce the spread of impulse sound. By using acoustic deterrent technology, harbor porpoises can at least be scared away from the immediate vicinity of the detonation. The German Navy has already reacted by procuring deterrent technology, so-called “seal scarers”.

10/21/2020 | Press release No. 187/20 | Joint press release with the Federal Ministry of Defense

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