To build on this and a number of the other comments in here:
There are two general types of sonar. Active, and Passive. Passive sonar involves the process of listening for signals, categorizing their type and origin, and determining their range and bearing. This is a difficult task, though the world's most sophisticated navies can perform this well. It is the preferred method of detecting other submarines (or for submarines to detect other vessels) because it does not give away the location of itself.
Passive of course, has limitations. Variations in water conditions and temperatures, silencing techniques used in adversary craft, a limitations of one's own equipment can make passive difficult, if not impossible in some conditions. And even then, it is a best guess at detection. Passive sonar will give you a pretty close approximation under good conditions and a "well, he's out there" in the worse. (In the most high-tech vessels, it's a bit better than this, but I think I have the gist)
Active on the other hand, is precise. Very precise. It also means, the gig is up, because the emitting craft is heard by everyone, extremely clearly. An active ping that gives a good return can give you precise range and bearing, and in some cases, velocity. It's of limited range, so typically submarines will hunt with passive and use active in the closing stages of an engagement.
Typically when I read about active sonar harming wildlife, it's in reference to the large active arrays carried by destroyers and submarines. Active is used by sonobouys, navigation equipment, and torpedoes as well, but these are typically lower power output.
The active array on a warship however, is generally massive, especially on a modern attack sub. They're powerful, and will produce pings against objects at thousands of yards. (I've even read that some British subs, such as the Trafalgar class, can bounce a signal off the bottom of the seabed, and get a return on a distance object from the reflected bounce.)
These massive arrays are important, because if you suspect an adversary has been tracking you passively, but you can't find them, then active scan can save you by alerting you to where they are. Tactically, it is a last ditch option, or the closing move in an engagement, and it's not unusual to see a safety cover over the switch to an active array. But it does have a purpose, and the Navy, justifiably so, does need to train with it.
But it does come with a cost, and it won't take long for one to search google for images of whale and dolphins with their ears literally blown to shreds because of an active scan.
I sympathize with both sides on this one, and I'm glad a settlement was reached that hopefully produces a good compromise.
Is not only a question of sympathy. One of the sides is breaking the law. In most countries is a crime to harass or kill a protected or critically endangered species.
The typical actitude in the last years was "dunno what happened, not my problem and the next week we'll be in Melbourne so, good luck".
And really is a problem that you created for somebody because:
1-A dead whale floating 10cm under the surface could easily wander with the sea currents, go unnoticed and crash with a ferry.
2-A dozen of rotten 2500 Kg carcasses stranding in a beach is a public emergence. It will contaminate waters and sand used by literally millions of tourists with dangerous bacteria and the most foetid rancid fat that you can imagine. Is expensive to clean the area again.
3-Is also a potential "bomb", because rotten cetaceans explode, literally. I have stabbed several.
4-The blubber floats. If in the water will atract sharks from open sea to coastal areas and beaches.
5-You could kill a fisherman by mistake with your sonar, or explode the ears of a silicon valley tycoon or an US senator enjoying an expensive diving holidays with the family, or whatever...
So is obvious that is in our best interest to put some limits to the army paranoia. You could estimate the probability of a third country making a first strike and starting a war in a scenery of peace, and I bet that is very low.
Is obvious also that we need to design much better 'high energy' sonars (most sonars are not a problem at all) or just to improve satellite surveillance, or maybe create autonomous robot-cameras that can go and explore silently a 'treat' instead to blow up all just because you get nervous...
And is in our best interest also to protect cetaceans, because an unbalanced marine ecosystem without cetaceans means probably lots of mesopelagic squids (unedible), much less fishes and famine for millions of humans.
There are two general types of sonar. Active, and Passive. Passive sonar involves the process of listening for signals, categorizing their type and origin, and determining their range and bearing. This is a difficult task, though the world's most sophisticated navies can perform this well. It is the preferred method of detecting other submarines (or for submarines to detect other vessels) because it does not give away the location of itself.
Passive of course, has limitations. Variations in water conditions and temperatures, silencing techniques used in adversary craft, a limitations of one's own equipment can make passive difficult, if not impossible in some conditions. And even then, it is a best guess at detection. Passive sonar will give you a pretty close approximation under good conditions and a "well, he's out there" in the worse. (In the most high-tech vessels, it's a bit better than this, but I think I have the gist)
Active on the other hand, is precise. Very precise. It also means, the gig is up, because the emitting craft is heard by everyone, extremely clearly. An active ping that gives a good return can give you precise range and bearing, and in some cases, velocity. It's of limited range, so typically submarines will hunt with passive and use active in the closing stages of an engagement.
Typically when I read about active sonar harming wildlife, it's in reference to the large active arrays carried by destroyers and submarines. Active is used by sonobouys, navigation equipment, and torpedoes as well, but these are typically lower power output.
The active array on a warship however, is generally massive, especially on a modern attack sub. They're powerful, and will produce pings against objects at thousands of yards. (I've even read that some British subs, such as the Trafalgar class, can bounce a signal off the bottom of the seabed, and get a return on a distance object from the reflected bounce.)
These massive arrays are important, because if you suspect an adversary has been tracking you passively, but you can't find them, then active scan can save you by alerting you to where they are. Tactically, it is a last ditch option, or the closing move in an engagement, and it's not unusual to see a safety cover over the switch to an active array. But it does have a purpose, and the Navy, justifiably so, does need to train with it.
But it does come with a cost, and it won't take long for one to search google for images of whale and dolphins with their ears literally blown to shreds because of an active scan.
I sympathize with both sides on this one, and I'm glad a settlement was reached that hopefully produces a good compromise.