Page 92 - Summer2020

SPOOKED!
Truth be told, we anglers simply don’t know what fish can and can’t hear. We’re not acoustic scientists (well, at least not most of us!), and we’re certainly not experts on fish beyond knowing how to trick them into biting. We spend untold sums of money on boats, rods and reels, lures, and other gear; we spend day after day at sea; we dedicate countless hours to figuring out how to fool those fish and take home dinner. But aside from a few direct observations, we don’t really know — know — just exactly which of these sounds that we’re making are heard by the fish, much less which are scaring them off. And for that matter, we also don’t know what sounds we’re making that might actually attract fish.
We don’t know if the fish are hearing these sounds at all or if they are (or are not) feeling them via the lateral line. We don’t know if the sounds we’re making are skipping off the surface of the water or if they’re being projected down through the hulls of our boats. We don’t know if an open aluminum hull does a great job of projecting sound through the water, whereas a fiberglass hull does not or vice versa. In fact, there’s a whole lot about sounds, fish, and what fish hear that we anglers don’t know. We may think we know, but...
Many years ago while doing research for an article in Boating magazine, my team and I used a hydrophone to record underwater sounds while fishing. We were curi- ous to find out what the fish that we were trying to catch might be hearing so we tried towing the hydrophone just under the surface among the lures in a trolling spread. Then we tried dropping it straight down at various depths under an anchored boat where our baits were being fished. One of the most fascinating discoveries we made was that we didn’t hear what we had expected. While trolling, we clearly heard human voices as people talked, but we could barely make out the rumble of the diesel engines, a dominant sound above the waterline. While at anchor, we heard the tell-tail (a stream of cooling water expelled from an outboard motor) splashing on the sur- face, yet we didn’t hear the motor itself. And while trying
to move the boat with as much stealth as possible, the sound of a push pole (usually thought of as the quietest form of propulsion) crunching sand and shells was nota- bly louder than the propeller noise created by an electric motor moving the boat at the same speed.
But you know what we didn’t find out? What those fish heard. We discovered what we could hear beneath the surface with our human ears, but as for the fish...well, they weren’t telling.
I know darn well that virtually everyone reading this right now knows one heck of a lot more about acoustics than I ever will. And there may even be some anglers among you. But as a 30-year veteran of the fishing field, I’d assert that I probably know the mind of a fisherman as well as anyone on the planet. And one thing I know for sure is that we anglers are quite concerned with catch- ing more and bigger (read older and wiser) fish, which means understanding how to avoid spooking them. That includes how we trigger senses other than hearing, such as sight and even taste. But in this layman’s world, I want to know everything I can about how sounds travel into and through the deep blue and just which of them those fish hear. And it’s a fair bet that this same curiosity runs through other hobbies and professions. Wouldn’t some- one training their dog want to know what pitch whistle was best for giving commands from afar? Doesn’t a ship’s captain want to understand how his or her hearing is affected by fog? Shouldn’t a musician know how to best set up in a venue to take advantage of the acoustics they’re presented with?
I can’t answer any of these questions. But maybe you can.
Contact Information
Lenny Rudow ultangler@gmail.com Edgewater, Maryland
92 Acoustics Today • Summer 2020