Environmental effects of sonar

Marine mammals use sound for the location of prey and predators as well as for communication and navigation. While there are certainly gaps in our knowledge in this field, we have to assume that there is probably a link between, for instance, sonar operations and the (apparently inexplicable) stranding incidents of marine mammals like whales.

Many governments are taking account of this and employ very strict regulations to govern the use of sonar. In practice this means:

• meticulous planning of sonar activities;
• verifying whether marine mammals are present in the operating area before the use of sonar is permitted;
• if they are indeed present, determining the effect of the sonar sound before making use of high-power equipment.

Animal-friendly solution

TNO has developed a software package, SAKAMATA, that helps the sonar operator to carry out his work in a more animal-friendly way. Pushing a button allows him to check which marine mammals are likely to be in his operating area and how sensitive their hearing is. A database in SAKAMATA also caters for the audiovisual monitoring of marine mammals.

The system generates advice for using sonar in each operating area. Part of this advice is a 'ramp-up scheme' that takes account of the sonar specifications, the environmental conditions and the types of marine mammals present in the operating area. SAKAMATA helps preventing hearing damage in marine mammals and gives the animals the opportunity to seek a quieter area during a sonar operation.