Sound and Sonar Issues

While there are many manmade sounds being generated in the oceans, we are most urgently concerned with the loudest: Military sonars and industrial exploration (for oil and gas, ocean mapping, etc.).

These are among the most intense sounds produced by man, and they're being used in an environment that is particularly vulnerable to acoustic insult... The extent of that vulnerability is just beginning to be understood.

MILITARY SONARS

Since 1996, when an article appeared in Nature -- one of the world's most prestigious scientific journals -- on the stranding of 12 Cuvier's beaked whales across a 40-mile stretch of Greek beach, military sonars have come under increased scrutiny. In this incident, low-frequency sonar was used during NATO military exercises in the Mediterranean Sea.

In other parts of the world, when whales and dolphins started washing ashore dead with no visible injuries (Canary Islands, Puget Sound) or stranded live in shallow water (Bahamas), mid-frequency sonars were also implicated...  More  

SEISMIC EXPLORATION

The term "seismic exploration" can be a little misleading. It doesn't necessarily mean looking for literal earthquake faults, although it is used for that purpose. For the oil and gas industry it means looking for the types of strata that hold fossil fuels. Seismic exploration is also used for mapping the ocean floor's topography.

It is a problem because most seismic surveying work is conducted round the clock for weeks and sometimes months at a time. The airguns are blasted every few seconds, 24 hours a day...  More