By: Joe Gasper

What is Sonar?Sonar is originally a acronym for sound navigation and ranging

Sonar is used to detect other sea vessels, and to communicate between those vessels

Also sonar is used for navigation

Two Types of Sonar

Active SonarWhen sounds are

emitted in pulses, and listing for echo's

Passive SonarBasically used for

detecting noise made by other vessels

Active Sonar Active sonar can detect vessels that are to quiet to be picked up by passive sonar

Active sonar is also used to detect marine mammals such as whales

Also active sonar detects marine mammals in shipping lanes, or in high sound pressure zones.

These high sound pressure zones are usually used for military exercise

Passive SonarPassive sonar picks up sounds using electronic listening equipment.

A target can be detected by the noise it makes from its machinery, the propeller, or the sound of the water passing around the vessel as it travels.

What Type Causes More Harm?

The active sonar is what causes the problems for the whales

It is usually beaked whales beachedBeaked whales are mainly affected by the

active sonar

Difference in HertzMany military’s are now focusing on new

types of sonar

Military’s are testing and finding that low frequency sonar are not affecting, or stranding the beaked whales

This may led to a compromise between the military and environmentalists trying to protect the whales

Hertz Measurements

Low frequency sonar is different from mid frequency sonar

Low frequency sonar puts out between 100 and 300 hertz, whereas mid frequency sonar puts out between 2,000 and 10,000 hertz

How Military Sonar Affects WhalesWhy are whales beaching themselves

from the sonar?Researchers believe that the sonar causes

decomposition sickness or “bends”This is common among scuba divers that

rise to the surface to quick

Research Behind the StrandingIn 2002 there were autopsies preformed on

stranded beaked whalesFour hours after a military sonar test started

the beaked whales started to beach themselves

What Did the Autopsies Reveal?The researchers had eight beached specimen

to examineWhen they were performing the autopsies

they found two problems

Gas Bubbles in Blood Vessels

Hemorrhaged Vital Organs

Referenceshttp://www.biology-blog.com

http://www.whaleresearch.org

http://onemoregeneration.org

http://www.surtass-lfa-eis.com

http://misclab.umeoce.maine.edu

http://www.cascadiaresearch.org

http://medinfo.psu.ac.th/pr/MedBoard/Img/20100216110043.jpg

http://news.nationalgeographic.com/news/2004/03/0331_040331_whalesincrisis.html

http://news.nationalgeographic.com/news/2003/10/1008_031008_whalebends.html