What are strange sounds at my dock??
I dock my 32' cruiser at a marina on West Harbor near Port Clinton Oh. Each evening there are fairly loud sounds coming from the boat or water surrounding the boat. It sounds similar to a frog croaking. It's almost continuous sound broken every 10 seconds or so for a couple seconds only to resume. At first I thought it was an electrical or mechanical issue with my boat and I spent a lot of time searching for the source. Didn't find anything. Then I walked down the docks and I can hear the same sound, so it isn't just my boat. The noise continues until about 11:00 or midnight, then quiets down and quits. I've never heard the noise in the morning or afternoon.
I've read on this and other sites that saltwater boaters contend with noises that come from saltwater shrimp and other saltwater creatures. I've not been able to find any information on anything like this in fresh water.
Has anyone experienced anything like this and can you identify the source of the noise?