If you enjoy Chesapeake Bay fishing, or any sort of fishing for that matter, it's a safe bet that you'd like to catch more fish. Heck, that’s why your eyes are skimming these words at this very moment. You’re thinking all the time about how to get more bites, increase your hook-up ratio, and out-fish other anglers. But, how often do you consider the opposite side of the equation: what might you be doing that discourages fish from biting? Most of us don’t think about this nearly enough. And while boat noise is the one thing many of us do consider as a potential fish-spooking factor, there’s actually a range of actions that we anglers do which has a clearly detrimental effect on our catch rates. Ready to stop scaring away the fish? Then you need to use common sense when considering these fish senses.

deet chemical composition scares fish
The chemical composition of DEET, one of the world’s most effective fish-repelling substances; if you want to scare off some fish, this stuff is just the ticket.

What Fish Smell

Sure, you might use scented lures and think about the scent trail created by baits, chum slicks, and attractants. But when’s the last time you paid attention to what the fish don’t like to smell? While on a week-long press gig fishing for specks and reds in Port Aransas, Texas, I had the opportunity to meet Berkeley scientist John Prochnow, a key figure in the creation of GULP! baits. And I asked him if there were any smells he came across in his research that actually repelled fish rather than attracting them.

“Absolutely,” Prochnow told me. “The worst is DEET, the active ingredient in nearly every form of bug repellent.”

To test his claim for myself, the next evening I sprayed myself down with a popular bug repellent and made sure some “accidentally” got rubbed off onto my hands. Then, I walked down to the lighted pier at the fish camp with another angler on the trip. We rigged up identical soft plastic jigs (five-inch chartreuse Bass Assassins), and started casting. He out-caught me five to one before I couldn’t stand it any longer, and went inside to wash up.

Lesson learned: avoid bug repellent entirely, if you want to catch fish. Prochnow also mentioned that suntan lotions with heavy perfume were another item that can put fish off their feed. Interestingly, some other items that people believe put a scent on a bait, most notably gasoline and WD-40, can’t even be detected by the fish.

“It’s like putting a square peg in a round hole,” Prochnow explained. “The fish’s chemo-receptors simply can’t register some chemicals, including gasoline and many refined oil products.”

What Fish See

Sight is certainly a sense that most anglers focus on, though again, we almost certainly focus on what attracts fish as opposed to what might be scaring them. Unfortunately, it’s tough (read: impossible) for us to know if we see things the same as the fish do. To try to gain some insight, however, one could send scuba divers over the side of the boat and then troll around them with hookless baits and lures. So that’s exactly what we did back when I was on staff at Boating Magazine (and magazines had the budgets to do silly stuff like run scuba divers 60 miles out to Poor Man’s Canyon, and troll over them all day).

tuna eye
Tuna have big eyes, and can be spooked by what they see... or not, as was the case with this catch!

We learned quite a bit during the experience. As one might expect, the most natural-looking bait was a naked ballyhoo. Skirted ballyhoo with purple or black drew the diver’s attention from a distance. The same was true for blue/white combinations. And scientists often tell us that in nature, contrast is what draws the eye more than a specific color. Of course, if you’re a fisherman you probably already know that some of the most effective lures boast significant contrast — blue/white Islanders, and red/white Mir-O-Lures, for example. And surely, choosing a particular color pattern won’t scare off fish, right?

We didn’t think so either. But the most interesting discovery generated by this (ahem) field work was completely unexpected: The V-shaped wake made by the leader entering the water was actually more visible then the lures or baits were, in many cases. And, according to our divers, it looked completely un-natural when the line entered the water anywhere near the bait. That’s a detail well worth consideration, the next time you choose whether to run a surface trolling line directly from a rod tip, or change the angle of attack with a flat line clip; when you choose which rigs to set from which outrigger clips; and whether you decide to add that chin weight, or not.

Another interesting discovery: all of the leaders (50-, 80-, and 130-pound test) were visible to the divers below the surface, including (though noticeably less so) fluorocarbon. Thinner diameter leaders were much harder to spot then heavier ones, to the extent that 50 pound mono was less visible than 80 pound fluoro. So minimizing leader diameter is another important consideration to take into account even when trolling.

What Fish Hear

If you’ve ever been fishing on the flats in Florida, you already know that the guides down there take noise quite seriously. In fact, if you slam a hatch on the boat, stomp on the deck, or even talk loudly, you’ll be rewarded with a glare — as the fish you were stalking shoots off into the distance. As we already noted, many anglers in this neck of the woods do realize that boat noise can have scare fish. But in Mid-Atlantic waters, we usually can’t see the fish’s reaction to the sounds we make and as a result, we have an “out of sight out of mind” mentality. In fact, every time you make a loud noise, every fish within casting distance can “hear” you, sensing the vibrations made by loud noises with its lateral line.

During another stint of field work, we tried dropping a hydrophone down under the boat to different depths, and listening to the sound levels created by different things we anglers do on a regular basis. The hydrophone was interfaced with a db-A meter (the device police use to measure sound levels at rowdy parties) so each noise could be measured.

As one might expect, outboard motors created some noise under the boat. When idling along both, two-strokes, four-strokes, and electric trolling motors all make a bit of prop noise, the volume of which was directly related to speed. But while a four-stroke remains very quiet in or out of gear, a two-stroke creates loud chatter when shifted into neutral. The same rattle-clank-bang of metal on metal which you hear above the water transmits below, as well. So if you run a two-stroke, you’re best served by motoring towards your hotspot and shutting down while the motor remains in gear, instead of shifting into neutral and allowing the motor to idle.

With both types of motors, however, shifting into and out of gear created the loudest sound and caused a hair-raising metal-on-metal “bang.” Starting an outboard also created a metal-on-metal noise (though not as loud as shifting) when the starter engaged the flywheel.

Engine noise was, however, only part of the story. Dragging a tacklebox across a fiberglass deck, slamming a hatch, dropping a lead weight to the deck, and stomping on the deck all created loud, startling noises 20 feet down. Even dropping a rod into a holder was detectable. In short, any physical contact between two hard items spiked the db-A meter — and could scare off your quarry.

Truly bizarre implications arose when the hydrophone was towed behind the boat in an offshore spread. With the hydrophone set about 50 feet behind three types of boats (a stern-drive, twin-diesel inboard, and outboard) in all three cases, the loudest sound heard near the baits was people’s voices. The tones of regular conversation could be clearly heard over and above all engine and propeller noise, and when someone yelled from the bridge to the cockpit or vise-versa, their voice practically drowned out the other sounds heard in the spread.

Most of us have, at one time or another, had a billfish enter the spread, play with a bait or two, then leave. It’s usually said that these fish were “window-shoppers,” not aggressive nor ready to feed. But if this were the case, why would they bother entering the spread and billing the baits in the first place? A more likely explanation to their behavior lies in what the crew does when someone saw that bill: they yell at the top of their lungs, jump from their seat to the deck, dart across the cockpit…and, how many times has that marlin swam off, without ever eating a ballyhoo? Draw your own conclusions; I know I have.

For an in-depth examination of how and what fish hear, see The Fish Are Listening, at BoatU.S.

What Fish Feel

Another sound few of us ever think about is that made by our fishfinders. Many electronics experts will swear that a fish can’t hear a fishfinder as it’s pinging away. Fire up a fairly powerful unit with a transom-mount transducer, however, and you can hear the “tock… tock… tock” yourself, if you lean over the transom. That doesn’t necessarily mean fish can hear it, of course, but while doing research for an article several years ago, I saw something with my own eyes that convinced me beyond the shadow of a doubt that fish, at least some species, can sense an active fishfinder.

For this gig, we were granted permission to launch a small boat in the massive 500,000-gallon saltwater tank in the National Aquarium in Baltimore. I’d mounted three fishfinders and transducers on it; all were fairly weak units in the 100 to 300 watt range. A second journalist was posted two flights below, watching as fish passed under the boat. We communicated via FRS radio, and she alerted me whenever a specific fish was about to be pinged by the finders. Our mission was to determine if I could differentiate between species with any of the three units. Nope — turns out it was impossible to tell if the marks came from a snook or a sand tiger.

The fascinating discovery we made, however, was that fish started avoiding the boat when the fishfinders were fired up. Sharks and rays, in particular, showed a clear dislike of swimming through the transducer cone, but other fish did begin swerving around to keep from going under the boat.

catching fish from a boat
Whatever this fish may have heard or felt, it obviously wasn't enough to spook it. Or, for that matter, those sounds and vibrations might have attracted it to the boat.

Now, we’ve all caught fish with an active fishfinder, and I’m not about to claim fish are aggravated by those sound waves. But they can in fact detect them, which means the fishfinder could have an effect, be it positive or negative, at any given time in any given situation.

When you take all of the fish’s senses into account, it becomes easy to see how we could be scaring away far more fish then we attract. In fact, sometimes it makes you wonder how we catch anything at all. So remember to consider all of these factors the next time you go fishing — it’s a sure bet that doing so will boost your catch rate.