August 05, 2020
By Tom Rosenbauer
When I teach the advanced dry-fly fishing course at the School of Trout each summer on the Henry’s Fork, one of the most important ideas I pass along to the students is that you should try to get as close as possible to the trout you are after—close enough to the fish to make an accurate cast, but not so close you spook them.
Everyone wants a definite answer to “How close can you get?” but there are no absolutes in this discussion. But I know from answering questions on podcasts, in fishing schools, and at fishing shows that these are honest and valid questions. People can cast well, and know how to tie on a fly, but the first step out of their vehicle is often still confusing and intimidating. Sometimes you make mistakes. Learn from them.
When you see fish rising, or when you approach a piece of water you suspect holds trout, there is always a judgment call between trying to get as close as possible so that you can make an accurate cast, and the idea that the closer you get to a fish, the more likely you will scare it. Every piece of water is different, and in truth every single fish is different in the distance at which they suspect your presence.
Fish don’t always spook when they see you—sometimes they sense a difference in the surface of the water, and sometimes they hear an underwater sound that is not part of the background noise. One fish in a pool might be in fast water at the head, surrounded by bubbles and the noise of rushing water, and will let you get 20 feet away. A fish in the middle of the pool, where the surface is smooth and quiet, might not let you get within 60 feet. And to compound it further, that spooky fish in the middle of the pool might let you close the distance to half that if it’s just before dark, if it’s feeding heavily, or if rain disturbs the surface. You are going to get it wrong, and you will spook fish. It’s part of the game, so don’t agonize over it. Move on to the next one.
One factor in bigger rivers is the smoothness of the water’s surface, along with its velocity. On long, slow flats, working upstream seems to be a smarter option, because you will always be moving up behind the fish. However, when you wade upstream you push more water because you fight the current, and pushing water makes more noise and creates waves on the surface that are sometimes not so apparent to you but extremely visible to the fish. These waves distort an ordinarily smooth surface and wiggle the edges of a fish’s window in a way that is not part of the normal background movement they see. They know something is approaching long before they see anything above the water.
In this case, sliding downstream carefully, working with the current instead of pushing wakes upstream, can sometimes get you closer to a fish than sneaking up behind it. Of course, in a riffle any wakes you push are immediately dissipated in all the rough water around you, so it’s seldom a concern in faster or riffled water. But on a smooth surface with slow current, you can push a wake 50 yards or more upstream of your position.
One mitigating factor in your ability to get close to trout is how eagerly they’re feeding. When a fish is feeding every few seconds, you can get a lot closer, sometimes right on top of the fish. This is especially true in low-light periods, but they can be less spooky even in the middle of the day. I suspect it is their inability to focus much of their brain resources in avoiding predators when food is abundant—apparently the importance of getting food when it is abundant trumps the increased exposure to predators in the evolutionary winnowing of genes that get passed on to the next generation.
It could also be a vision factor, as perhaps when their brain is focused on tiny objects close to them in the water, trout do not recognize larger objects above the water. Empirically, you see this on some rivers like the Bighorn in Montana. This rich tailwater always has some kind of food drifting in the water column, and if you have fished there, you know that the trout are seldom bothered much by either wading anglers or drift boats. Unless you walk right on top of them, they continue to feed despite the tremendous commotion produced by hundreds of anglers passing by them each day.
You might suggest that this is a conditioning factor, fish seeing people day in and day out—but I don’t think it is. The Battenkill is a river that also suffers from heavy boat traffic during the summer, in this case rafts of inner tubes and canoes manned by people looking to escape the heat of the summer in the Battenkill Valley. The Battenkill is not a rich stream, offering up its insect hatches in fits and starts, and in my lifetime I have watched it go from a river where fish would be out in the open and occasionally feeding during the day to one where they stay hidden in the middle of the day and only come out to feed in the evening and early morning. Those fish may be conditioned to the heavy boat traffic, but as they are not as distracted by food all day long, they stay out of the way.
Sound waves move five times faster and four times farther in water than they do in air. This is a scary fact, because it seems like any little motion we make in a river will alert wary trout to our presence. Luckily, there is more science behind this basic science. The most important part of this is that fish can be broadly grouped into two types with regard to hearing: generalists and specialists.
Specialists, which include carp, catfish, and shad, have a broader band of hearing and can hear noises from much farther away. They can detect both particle motion and changes in pressure waves created by underwater sounds because they use both their inner ears and their swim bladders to detect noises. Luckily, trout, bass, and sunfish do not have the specialized structures of these other fish and use only what is called near-field hearing, which is based on particle motion as opposed to pressure changes, and the near-field component of noise decays rapidly. This may be why carp are so much harder to approach than trout, even in relatively muddy water.
In addition, structures in the water, like rocks and weeds, help ameliorate sound waves and any ambient noise in the water caused by riffles, and pocketwater also masks the noises we make. Deep water also allows noise to travel farther because there is less interaction between the sound waves and the bottom. So if trout can only hear sounds from a few feet away, why do they spook when wading soles with metal studs are scraped along the rocks 50 feet away? This was the question posed by John Mosovsky in a paper titled “Understanding Bioacoustics to Catch More Fish,” where much of my understanding of trout hearing discussed here came from.
I have been wearing metal studs on my wading shoes for many years, and I can’t say that I have noticed trout any spookier when I am wearing studs than when I am wearing felts. In fact, a number of times I have approached happily feeding trout to within 30 feet and scraped my metal studs on the rocks without noticing any change in their behavior. But I must stress that when I scraped my studs on the bottom, I was careful not to make any surface disturbances on the water at the same time. Trout are far more visually oriented than aurally oriented. I suspect that sloppy wading, pushing more visible waves on the surface of the water, or abrupt movements of your body above the water, due to studded soles being less stable than felt on some kinds of rocks, are far more risky for spooking trout than the noises you make.
But what about the lateral line? The lateral line system is a series of pores lined with specialized hair cells that are joined by a canal that runs almost the full length of a fish, especially in the head area. It allows fish to “hear” prey items in dirty water, one reason why streamer flies with bulky heads, lots of hackle, or deer hair are so effective in dirty water, because trout sense the vibrations in the water caused by these. The lateral line system also allows trout to detect changes in current flow around their bodies to help them stay oriented properly in the current. But again, the lateral line system works on near-field particle disturbances. It is not like an early-warning system radar array. A trout can’t detect your Muddler Minnow in dirty water from more than a few feet away. Thus the lateral line system is not going to detect the scrape of a metal-tipped wading staff from more than a few feet away.
Sometimes, a single fish in a spot can bolt up through the entire pool and spook every other fish living there. This makes intuitive sense, because a fish seeing another fish frightened enough to swim quickly to the security of deep water, or a riffle, or a log should raise the alarm. I have seen cases where this is true, especially in the low, clear water of summer when you can see every stone on the bottom. You approach the tail of a pool, and you don’t see the fish feeding just in front of a rock in the tail. It senses you and darts to the head of the pool, where deep, broken water makes it feel secure. As it swims to the head, you suddenly see a half dozen other fish follow it to the same place. You then wonder if it’s even worth it to fish that pool. Often it is worth a try. Some other fish in the pool might have been visually isolated from the ones that spooked. Perhaps they were tight to the opposite bank in a deep slot, or perhaps some were on the far side of a rock pile and did not notice the other ones bolting. I have sometimes watched a single fish spook up through a pool and swim right past other fish that were busily feeding, and kept on feeding without missing a beat.
You can even play a fish through a pool, and despite the desperate struggles of the fish you have hooked, others don’t seem to care. If it’s a small fish you’ve hooked, bigger ones will often chase it and try to eat it. It’s always good practice to try to lead a fish you have hooked away from places you suspect might hold other trout, but sometimes trout, especially big ones, call most of the shots, at least in the initial part of the battle, and you have to let them churn up seemingly good water. In that case, if you feel strongly that the pool holds more fish, it’s wise to rest the pool by stepping away from the water, either moving to the shallows or sitting on the bank, and giving it a 10- to 15-minute breather.
In approaching trout, I know that you want some concrete answers so that you can stalk trout confidently in any situation. I don’t have any easy answers, and if anybody tells you different, they haven’t studied trout behavior closely. My own observations that sometimes trout spook at the slightest insult while others seem to be more carefree are backed up by scientific studies. A team of scientists in Canada studied a group of rainbow trout and found that in any given population, there are shy trout and bold trout. The shy trout retain long memories of predator threats and spook at the slightest hint of trouble. The bold individuals seem to forget these dangerous experiences within a couple of days and concentrate more on feeding than on avoiding predators. And like all things in nature, most trout in a population probably fall on a continuum between very shy and very bold.
A similar study of brown trout in Sweden gave further evidence to the fact that trout have individual personalities. When a novel object was released into an aquarium full of brown trout, some immediately investigated the object while others fled to corners of the aquarium in fright. You would suspect that the bolder trout, who fed more often, would be the most successful in the wild, but in the Swedish study when the fish were released into the wild, it was the shy individuals that grew most rapidly. Of course, the relative success of a shy or bold trout probably varies with environment, and even in a single pool there might be places better suited to shy or bold fish. This is likely why wild populations continue to pass on genes of both the shy and bold personalities, because in any given year class, survival of the individuals that go on to reproduce varies with the interaction of a fish’s personality and the environment it chooses.
Change Location or Change Flies?
What should I do if I’m not catching fish? Should I change spots or change my fly pattern? This is a question that all of us face almost every time we’re on a river, and if you think this is a conundrum only for novices, you are mistaken. The choice you make here is one of those aspects that makes fly fishing—in fact, fishing in general—so fascinating and mysterious. But when you finally find something that works, it’s a feeling of accomplishment that can make your day.
Much depends on how well you know a river. If you caught fish in a spot yesterday or last week or last month, as long as the water temperature or water level has not changed significantly, it might be best to stick with a place you know holds fish. However, you should temper this with the thought that the more time you spend casting over a pool, the greater the chance you have spooked the fish and put them off the feed. But if you stay off to the side of the fish-holding water and have not ripped your line off the water a number of times, you may be able to fish the same place for an hour or more.
Riffled or deep water is best when you plan on parking yourself in one spot for any length of time, because fish feel more secure when the surface is disturbed or the water is deep. If you are fishing over flat, shallow water, the meter runs quicker because fish there won’t tolerate as much disturbance.
Regarding fly changes, if the water is below 50 degrees and no insects are hatching, you may want to stick with a fly you know should be successful longer than you would when the water is warmer and the fish more active. This is because in cold water, you may have to place your fly in exactly the right place many times before you put it right in front of a trout that is not inclined to move. On the other hand, if water temperatures are between 55 and 65 degrees, trout should be aggressively feeding.
If you are sure you have placed your fly in the right place with the right presentation more than a dozen times, it’s time to try a new fly, or perhaps just alter your technique.
If you are fishing nymphs, try setting your strike indicator deeper or adding a heavier fly to your tippet in case you are not getting deep enough. If you are fishing dry flies, try adding a second, smaller fly as a dropper. If you are fishing streamers, change the angle you cast relative to the current, try a faster or slower retrieve speed, or try an erratic retrieve.
If you see insects hatching or laying eggs, my best advice is to keep moving until you find rising fish or a place where you get a strike in 10 casts or fewer with a nymph. With a hatch in progress, it’s almost certain that trout will be feeding on insects somewhere, and it’s amazing how fish respond to an insect hatch in one pool and not one just above it. I can’t tell you how many nights I have parked my butt on the bank of a favorite pool in the Battenkill in the evening, watching Hendrickson mayfly spinners fall to the water without a single trout responding to them, only to go to the office the next morning and discover that some of my fishing buddies were covered up in rising fish just a few miles downstream.
Even if you don’t find rising fish, you might still try a dry fly or nymph in the faster water because fish may be feeding only on the emerging larvae below the surface, or they may be rising unseen in the riffles. Trout can make extremely subtle, almost hidden rises in riffles, and unless you are staring directly at a spot, you may miss them entirely.
*Tom Rosenbauer is the author of dozens of books, and host of The Orvis Guide to Fly Fishing television series airing on the World Fishing Network on Tuesdays in April, May, and June 2020. This story is partially excerpted from his book Fly Fishing for Trout: The Next Level (Stackpole Books, 2016). The text came from Chapter 4, “How to Approach a River.”