Underwater environmental impact assessments on marine mammals and fish by high power anthropogenic radiated sound

摘要

A methodology to assess the environmental impacts from high power underwater sound sources on marine mammals and fish is presented. The methodology was first developed for low frequency navy sonar and was later extended to different types of high power underwater sound sources, including underwater blasting for demolition, shock testing and seismic surveys. The methodology assumes that any species of marine mammal or fish may be present and defines two impact zones corresponding to the limit of inner ear permanent injuries and the limit of temporary threshold shift in hearing. The size of the impact zones depends on several key factors: the level of the anthropogenic sound radiated underwater; its nature, such as the duration and frequency characteristics; and the sound propagation characteristics of the marine environment that are dependent on factors such as water depth and sea bed material. The methodology was first developed and tested by the UK Ministry of Defence to conduct underwater environmental impact assessments to protect underwater wildlife from low frequency sonar. It was later successfully applied to the demolition of the North Sea petrochemical Phillips 66 Maureen oil platform sub-structure. The methodology can be tailored to any specific marine species or generalised when any type of marine animal may be present. This means the methodology can be applied to a wide range of projects that need to use high-level underwater sound sources which may impact on marine fauna. The implementation of the methodology has ensured no incidents have occurred during the deployments of all low frequency sonar trials in the UK.