Little is known about the risks posed to cetacean populations by weapons of war that were dumped at sea. However, it is clear that the conventional ammunition removal by blasting is not only dangerous for humans, but also represents a particular hazard to cetaceans. High sound pressure and explosion-related shock waves can lead to severe injury and hearing impairment in marine mammals at considerable distance from detonation sites. In addition, the animals and their habitat may be affected by chemicals released due to the explosion or from decaying weapons.
Large quantities of ammunition from World Wars I and II as well as the cold war period are still found throughout the ASCOBANS Area. For example, in German waters of the North and Baltic Seas, an estimated amount of at least 500,000 tons of ammunition is still lying dormant. ASCOBANS members try to engage with the military officials and environmental agencies responsible for removing unexploded ordnance to make sure that it is done safely for any cetaceans present in the vicinity. Some Parties (e.g. Poland, Germany, Sweden and the United Kingdom) also reported that mitigation measures have already been put in already in place. Porpoises have been scared away from dangerous areas using pingers and small explosions. Bubble curtains were used (e.g. in German waters) to reduce the sound pressure level.
Underwater explosion of 300kg bomb in German North Sea © K. Lucke / FTZ Westküste