Do gag grouper "croak"?

I finally caught one my shallower grouper holes in Pensacola Bay with the right combination of conditions for me to freedive today. It was near high tide, so the current was very slight, and there had been clean gulf water coming in with little boat traffic all morning, so visibility was good by our standards (about 15-20').

So we marked the wreck with a buoy, and anchored up a short distance away so my boys could fish while I checked it out. I really didn't know if the conditions would be divable, so I figured I would make a quick bounce just to see and didn't take my gun. That won't happen again. The wreck (a 16' or so boat surrounded by about a dozen tires) is in 40' of water. At about 30' I paused and could see grouper everywhere. Quite a few looked legal, so I headed back for my gun, and the sweet floatline that John Hanson just built for me.

Armed now, I headed back down. Again, as I hit 30' or so, I had a clear view of the wreck, and a bunch of decent gags. I continued drifting down, and across the wreck, and lined up a shot on one. Right then, there came the strangest croaking sound. It was a very loud, BRRRUUP, BRRRUUP, and it was so forcefull that I actually felt it. Like when you drift over a little on the highway and hit those bumps they mold in the shoulder of the asphalt. Anyway, at the sound, every fish I could see, of every size and species, positively bolted. I'm not talking a little skittish flight here, and nothing like the way they ease off when I dive scuba. They dove immediately for any cover they could find. They were literally knocking each other out of the way to get into the wreck first. I made several subsequent dives, but only saw a fraction of the fish that were there at first.

This same noise happened when I last dove this wreck about 6 weeks ago. I have never heard it anywhere else. Anybody have any idea what it might be? On rare ocaisions, I have seen goliath grouper in the bay, but this wreck isn't big enough to hold one over 50 lbs or so.

I've never seen a hogfish here, but black drum is certainly a possibility. I've never seen one while diving, but I know they are fairly common a little further up in the bay.

it might be a Goliath Grouper like you said. I've heard GG do that on wrecks and reefs but never spook the fish like that. As we all know GG eat those gags, so that might be it... Those grouper may bet trained to hide whenever the GG's come around on that wreck cuz they get eaten! lol

I dont think that the croaking sound is coming from the movement of the tail but movement of air inside of the air bladder. Thats now drum/hogfish/most other fish make their croaking sound.

well if you put it that way, it sounds completely nonsensical. but yes, I think that there was a GG on the wreck. It may have come in off the tires just as TinMan came in, i dont know. All we can do is speculate.

I've heard GG's croak like that, i know that other fish do that too, but in order for them to split like that it would have had to frighten them a little bit. Maybe the other grouper didnt know that the GG was there...

The grouper probably didnt take off, they most likely hid in the wreck or took cover in the tires.

I've never heard a Goliath croak, so I dont know if that's what I heard. But if so, he wasn't inside the wreck because I could see pretty much everywhere inside of it and there was nowhere for a fish that large to hide.

Dan - It was not what I would describe as a boom, but more of and extended vibratory noise. Like what croakers and grunts make, but a zillion times louder.

Quote from LunkerBuster

Jeff, any possibility the noise was from the surface? could you locate the sound at all....I have never heard anything underwater as loud as you describe

Since I never saw the source, I guess anything is a possibility. But I have only heard the sound twice, and both times were on this wreck, and particularly right after I arrived. There were other species about (scamp, red snapper, and red grouper among others) but I have never heard any of those croak either.

It's not like it was deafening, but more like of a certain frequency that could be felt as much as heard. There was no particular affect on me, other than that little twinge you get when everything in the vacinity suddenly darts for cover and you find yourself just a little concerned about why.