I was out in my 15 Gregor aluminum a couple weeks back and forgot to ask this then. I heard a distinct sound that was like fine water drops hitting a shower stall or like sizzling bacon in a fry pan. It was very audible through the bottom of the boat (no deck boards). I thought battery acid had spilled in my boat from the sound. It occurred only over certain reefs (Dana Point area) in 20-40 feet. There were no bubbles coming up in the water. I heard from buddy Jeff that some kind of reef shrimp en masse produces the sound. The day he mentioned this we were in his Klamath aluminum off Laguna and I didn't hear it then so I thought he was joking. Any thoughts?

Perhaps, gravel being moved in the surge? Doubtfull considering the depth and description of the noise. But you gotta start somewhere. I used to hear noise kinda like you mentioned when I worked on the Sum Fun. Down below in the morning filling the freshwater tank, I'd hear what sounded liked crackling ice or something. I was told it was the barnacles on the metal hull, but never quite believed it. Very loud, until the 3 deisels were fired up. Then it was hard to even think.

I realize barnacles aren't the issue, just a similar noise.

What about marine mammals?

Amish Ed
You Can't Catch it again if
it's Dead!

Hi Ed, there was little water movement that morning--super calm. Maybe my boat being aluminum enhanced the sound--like the tin can on either end of the string? It sounded like little snapping claws or clicking tails--gobs of them.

fongster, I have noticed in my tin can that sometimes when another boat goes by it makes the most unusual vibration run through my boat, making a noise similar to what you are describing. Sometimes a boat will make the noise in my boat from several hundred yards away. Something about the vibration traveling through the water. One thing is for sure, the fish don't like it because I've never been bit when another boat was going by making my boat vibrate.

Good call Rob. I've had the same thing sitting on a surfboard. But then you almost feel as much as you hear it.

Amish Ed
You Can't Catch it again if
it's Dead!

It really gives some perspective on how noise travels through water. I wonder what the fish hear :-)

Mantis shrimp & some other types of shrimp like the pistol shrimp make a loud clicking noise at times. As a matter of fact in the Reef Aquarium world they are despised creatures as they will can eat smaller fish in your tank over time destroy live rock and corals and can be difficult to catch. I don't know how prevalent they are in our local waters but here are some links to some more info...

http://ozreef.org/reference/mantis_shrimp.html

http://www.savebay.org/aboutus/bb_spring_02/html/creature_feature.htm

Maybe????

Fongster, probably pistol shrimp you heard- they are small but loud, and thick around there- pull open a kelpfast washed up on the beach and there are tons of them, cool little guys. Very loud in an aquarium before they get eaten.

I've heard that noises like that can be attributed to photoplankton. At night once, I scooped up a bucket full of water that had those glowing little guys. The bucket made a bunch of snap-crackle-pop kind of noises. So maybe its those little guys? But would have to be a lot of them for you to be able to hear it during the day.