Effects on wildlife?

[Gargamel]

Thread may be a bit premature, but from what I'm reading, the active systems are on All the time correct?

In a sub, they rarely turn them on cause the detection goes both ways. In the ACTUV scenario, we don't care about counter-detection. So it's firing constantly correct?

I know there has been issues with active sonar affecting wild life in the past. I personally have been SCUBA diving and heard sonar when the navy was some miles away doing ASW exercizes. It was pretty distracting, and they were far enough away that we never even saw them on the surface. I can only imagine how creatures that use sonar to survive react to that type of noise.

I would assume that this topic probably has been discussed to death over in GT, but the ACTUV angle is thus:

Will this project even be allowed to start if they can't get past the environmental groups? I know they (Greenpeace, EPA, etc) have sued the Navy and won (or at least settled) to prevent active sonar usage in some areas. How's it going to go over when it's an unmanned drone blindly pinging away?

[TLAM Strike]

The ACTUV used MF and HF sonar, LF Sonar is what had a negative effect on whales.

[Gargamel]

Originally Posted by TLAM Strike

The ACTUV used MF and HF sonar, LF Sonar is what had a negative effect on whales.

Hmm... good point.... I think that was starting to dawn on me as I have been reading more.


Still gonna stir up some rabble rousers though. Unmanned sonar! nooooooo!

[Oberon]

I'm still trying to get my head around switching active sonar on and leaving it on....TIS NOT NORMAL...

[FERdeBOER]

Originally Posted by TLAM Strike

The ACTUV used MF and HF sonar, LF Sonar is what had a negative effect on whales.

You're not right, the problem with cetaceans is more about signal power than frequency. HF sonar is less harming because is rapidly absorbed by water, so is not likely to harm nearby cetaceans because they will likely be detected first at those distances, and active sonar use is forbidden in most of the navies when cetaceans are present. LF and MF sounds travel further and then the possibility to reach cetaceans out of visual or passive sonar range increases a lot.
MF sonar range is less than LF, but its accuracy is better so, what to do to increase detection range? Increase the signal power, and that's what can harm cetaceans.
Other reason about active sonar harming cetaceans is not the "direct hit" of active sonar over them, but the sudden and unexpected loud sound, that can scare the animals when deep-diving, forcing them to interrupt the action, surfacing too fast and thus suffering decompression injuries.

Yes, I study cetaceans (and sometimes I even get paid for it).

Edit: of course I'm talking about peace-time periods.

[TLAM Strike]

Originally Posted by Oberon

I'm still trying to get my head around switching active sonar on and leaving it on....TIS NOT NORMAL...

You have to think of the ACTUV not as a submarine but a surface ship. It basically is since it doesn't completely submerged.