Approximately two years ago 150 to 200 melon-headed whales were found in distress off the shores of Kaua'i. These whales are small and sociable creatures that usually stay in deep waters.

However, these whales were swimming in a close-knit group very close to the shoreline, less than 100 feet, said some of the bystanders.

The whales were clearly in distress and not exhibiting normal behavior. What caused this incident?

According to a recent report released by NOAA, the cause remains a mystery. Some folks were quick to point a finger at the Navy as it was conducting exercises about 20 miles away that day using sonar. However, I must stress again, NOAA found no definitive evidence that this was the cause of the incident. Sonar could not be ruled in, nor could it be ruled out.

Unbeknown to many is the fact that the Navy has an aggressive marine mammal protection program in place. These protective measures that the Navy employs are the most comprehensive in the world. For example, the Navy has developed software that tracks historical trends of marine mammal populations in the specific geographic area where ships are operating.

In addition, before using sonar, the commanding officer must confirm that there is negligible probability of harming a marine mammal before going active. The ship will have trained lookouts and airborne assets, when available, scan the area for marine mammals prior to commencing an exercise.

Ships must decrease sonar intensity if a marine mammal is found to be in danger of injury and will cease using active sonar before knowingly injuring any marine mammal. Ships will cease using active sonar if a marine mammal is detected within 200 yards of an active source.

The Navy is well aware of the fragile environment and the possible effect of sonar on marine mammals. That is why it plans exercises to carefully avoid major marine mammal concentration areas whenever possible. The Navy is truly dedicated to protecting marine mammals, as evidenced by the $10 million it spends annually on marine mammal research.

There is no doubt that sonar affects some marine mammals, but the critical point is that sonar is only a very small part of a much larger picture.

There are many other external factors that are in the ocean at any given time. These include volcanic eruptions, lightning strikes, supertankers, offshore drilling and others.

These factors, combined with pollution, commercial shipping, fisher entanglements, disease, parasite infection, ship strikes, trauma and other natural factors lead to approximately 3,500 marine mammals stranding every year on U.S. shores alone, according to NOAA.

Does sonar affect marine mammals? Yes. To what extent, we are not sure.

However, the Navy is taking aggressive steps to protect marine mammals and avoid engagement with them whenever possible and exhibiting sound environmental stewardship with our precious ocean resources.

Bob McDermott is a Marine veteran and executive director of the Navy League in Honolulu. He wrote this commentary for The Advertiser.