spt29970
Contributor
Dolphins and whales herd fish using bubble curtains, presumably without all the noise our regulators make, so it is reasonable to believe that the bubbles themselves do scare the fish to some extent.
Why do you think that bubbles generated by dolphins and whales are silent? The bubbles themselves are the source of the noise, regardless of who generates them. You can verify this yourself with a simple test. Descend about about 5 feet in a swimming pool and breathe slowly. Wait for the bubbles from your last exhale to hit the surface, then notice that it is virtually silent while you are inhaling. As soon as you exhale again, it suddenly gets noisy. If you are down more than about 15 feet, the bubbles from each breathe don't have a chance to reach the surface by the time you take the next one, so there are always bubbles in the water column and the noise never stops.