Out west in our clear deep reservoirs LMB commonly stablize their airbladder to be nuetral bouyant at 30 to 35 feet and spend a great deal of time suspended at that depth. I believe this gives them the opportunity to make quick runs toward the surface to capture baitfish above them, like threadfin shad or case deeper baitfish by running down into deeper and pushing the cold water baitfish, like trout, towards the surface.
Yes, thier airbladder's expand and contract within the 35 foot depth range, but it doesn't seem to hampered them greatly in catching prey and returning back to the 35 foot level to swallow it. I have never witnessed bass suspending any deeper than 35 feet try to run up to the suface, unless they were being hooked and pulled upwards by an angler.
IMO, barometric pressure has lttle affect on the basses airbladder, it's to minute a pressure change.
It takes several days for a bass to adjust the gas pressure within it's airbladder, that is why they make gradual depth level changes during normal migration seasonal periods, however as noted above , the bass can make quick runs up and down, they can't easily neutralize their bouyancy to suspend at a specific detph.
Having caught lake trout 150 feet deep and deeper, you see the trout release air bubbles during the fight, so they can and do adjust to depth changes quickly, however bass can't release the gases and fast pressure changes affect both their eyes and airbladder, so they have limits to the depth changes they can make without sever damage to critical organs. During the cold water period you may hook a bass in 30 feet of water, however that bass may have been suspended at 50 or more feet and move up to catch your lure, then you pulled it to the surface and that is a 50+ foot depth change, not 30 and the basses airbladder extends out it's mouth and eye bulge out from the pressure change.
WRB