Ask A Biologist: Do Pressured Fish Learn to Avoid Certain Lures?

On the flip side, theories do a terrific job of keeping the conversation going when the action is absolutely pathetic. It can’t be anything you’re doing wrong, right? It has to be the high sun, the dropping water, global warming, or a discharge of gas from one of the rings of Saturn. The rock bottom, which I’ve heard uttered several times is, “I don’t know, man, these fish must be sick or something.”

Arguably the most debated theory, however, is that after being pounded for too long, fish get conditioned to certain lures and won’t touch them anymore. It’s the go-to whenever last year’s hot bait suddenly isn’t cutting it. But is conditioning real, or do anglers simply get so confident in a lure that they put blinders on—consciously or subconsciously—and try to will it to work rather than think about other reasons it might not be producing anymore? Let’s shed some light on the facts and fallacies of fish conditioning.   

Under pressure
In the usual dog days of summer, boat launches might look like the 405 in pre-COVID times, while drift boat after drift boat float the Upper Madison Highway, I mean, River. Depending on your perspective, too many anglers might squash the solitude you seek when you go fishing. Further discontent may arise if you’re one of the people that believes increased fishing pressure equates to decreased catching.

The short answer is, “Yes,” increased pressure does play a role in the general willingness of fish to bite, but it’s not so cut and dry that it should become your go-to excuse when the bite sucks.

For context, angling techniques were invented at least 50,000 years ago as a means of providing food. As a recreational activity, the first known evidence traces back to an image from 3,200 years ago depicting an Egyptian noble returning a fish to the water. So, from one viewpoint, fish have had a long time to get conditioned to being hooked. So, why then do fish, which apparently have the ability to learn, still strike a red-and-white spoon with as much gusto today as they did in the 1940s and 50s? There are a couple factors at play.

Eat or be eaten
Catch-and-release fishing has become the norm for many anglers targeting a wide variety of species. While catch-and-release has proven benefits from a conservation standpoint, the bottom line is that it’s impossible to avoid putting or inflicting some level of injury or stress on the fish.

A fish’s life is a constant game of risk—eat or be eaten. Just like the suits on Wall Street, each individual fish within a population can tolerate different levels of risk. There’s a measureable spectrum from timid to bold in fish behavior. For growth and survival, there are advantages to each end of the spectrum. Put another way, extroverted people enjoy benefits from bar hopping on a Friday night (e.g. bold), while introverts might benefit from hanging out on their basement couch (e.g., timid). Bold fish are more likely to be caught by anglers. They’ll more readily take the big risk of attacking an unfamiliar food source (like a lure or fly) while gambling for the big reward of a big meal. Think pike, muskies, and big brown trout.

After release, the time to recover from capture-induced stress can be variable. Depending on the individual’s capture experience—the amount of time played on hook and line, the amount of time handled and exposed to air—a fish may learn to avoid similar situations that put them at risk. Likewise, during a pandemic, typically outgoing people may decide to stick to their couch rather than hitting the night clubs.

Timid fish are generally less susceptible to angling, but still must eat to survive. These fish, either by the innate or learned timidness, pick and choose feeding opportunities that minimize risk. Think of wary, wild brook trout or even bluegill. While “luck” comes into play for any single juvenile smallmouth bass surviving to 20-inches in adulthood, or for a stocked walleye fingerling to eventually achieve the angler-coveted 30-inch mark, there’s a behavioral aspect to their success as well. Bold behavior while feeding might get them eaten as young’uns but also might help boost their survival and overall population numbers as they mature

Various studies have concluded that sustained fishing effort can reduce angler catch rates via learned behavior from previous hook encounters. Of course, big waters with healthy populations can sustain more fishing pressure because so much acreage spreads it out. But regardless of waterbody, given reduced fishing pressure, angler success and catch rates can potentially recover, at least in the short term.

Learn or evolve?
While fish can adapt their behavior because of external stressors, it’s pretty difficult for a fish to learn to avoid lures when its fillets are bubbling in hot oil. That said, catch and release isn’t the only practice that affects fishes’ willingness to bite a hook. Highly harvested populations can also evolve to be more timid.

Where a fish lands on the timid-to-bold spectrum is, at least in part, a hereditary trait. As noted, bold fish are more likely to be caught by anglers. If catch and release in grease is the end result, the “boldness” of those fish is removed from the population—thus leaving the population, on average, slightly more timid.

During spawning periods, catch and release, with or without grease, leading to nest failures can create increasingly timid populations. Aggressive fish are more likely to be caught when guarding nests, and therefore, have a higher chance of nest failure if not released quickly and safely near the nest. Timid fish, that are not removed from nests as often, may have increased nesting success and thereby pass on the timid trait to more offspring. In this manner, given enough angling pressure over the long term, populations can become more difficult to catch, even if overall population numbers remain static.

So, yes, pressured fish can learn (or adapt) to avoid certain lures. How and whether to limit fishing pressure is a whole other topic with its own complexities for anglers and agencies alike. But how can you tip the scales in your favor to catch more fish, especially in pressured waters with conditioned fish?

An obvious choice is to go where others don’t. Drive an extra hour or two from populated areas. Or, if you can, fish mid-week and avoid weekend crowds. Or, maybe place your 25 horse outboard on the boat floor, lay skyward on the casting deck, and use your arms to shimmy your boat through an extremely low, long culvert under a highway to get to an otherwise inaccessible backwater. I’ve seen me do it. However, superfluous effort need not apply here—just break from the norm.

In metropolitan waters where 95% of anglers are throwing spinners and crankbaits, bring your fly rod. The fish of 10,000 casts might turn into the fish of 100 casts. I’ve seen it happen. Sure, stripping big muskie streamers on flat water all day can be laborious, but so is hucking a #10 double cowgirl. Just don’t forget the Tiger Balm.

You can also experiment with more subtle but potentially fruitful lure alterations. Use a rattling jig with your root beer grub to make your “crayfish” stand out in the crowd. Maybe add a twister tail to the treble hook of favorite inline spinner or spoon. Or switch from a regular stick bait to a jointed one. Anglers can also use cheap nail polish to quickly test new color schemes while on the water. A jointed perch Rapala with a red, nail-polish-painted back half? Yep, I’ve seen me do that too, and I out-fished my buddy and his regular ol’ floating perch Rapala by a 10-to-1 margin.

Classic fishing tales are often told of “Lake X” or “Area Lake” where fish are caught “on a hook in the water.” But fear not, even if you’re returning to the boat launch without a grandiose fishing story to tell, or newly proven theory, feel free to toss out “behavioral plasticity” or “fisheries-induced evolution” to the inquiring minds of fellow anglers. Maybe they’re legitimate excuses. Then again, maybe not. Nonetheless, thinking outside-the-box on pressured water can pay dividends for your ego and freezer.

No doubt, different species, different places, different weather and water conditions, different levels of fishing pressure, etc., will determine behavior. However, all else equal, science backs up the overarching notion of learned hook avoidance.