Sound Advice

Nick recommends being acutely aware of a trout’s auditory world when flyfishing.  

It’s obvious that flyfishing is a visual sport from the angler’s perspective. Sight fishing, or watching for indications of the fish taking the fly, or successfully landing the fish, all require the focus and attention of an angler’s eyes.

With this in mind, it’s little wonder that sound can take a back seat when assessing the ingredients for flyfishing success. While most flyfishers recognise that sound or vibration play a part to some degree (both positively and negatively), it’s worth looking a little more closely at the relevance of sound to the fish – and therefore the angler.

Sound principles

Because water has a higher density than air, it is far more efficient at the transmission of sound and vibration. Whales, for example, can communicate up to 8,000km or more through their low frequency calls. The water surface, however, acts as a reflective barrier, so that little sound escapes from the water to air. This is probably one reason the relevance of sound in fishing is underestimated. We can often see lots happening under the water, but rarely do we hear anything, unless that activity, like a splash, breaks the surface.

Listening to some fascinating podcasts on ABC Radio recently (some links at the end of this article) highlighted what a noisy natural environment it is under there. For example, the humble water boatman makes an incredibly loud cicada-like sound. Shrimps click, while other invertebrates also have distinctive and significant sound signatures. It’s certainly food for thought (so to speak!). We go to great pains to imitate the appearance of trout prey, but with little thought towards accurately mimicking its sounds.

Sound fishy?

Trout, as you would expect, are highly adapted to the noises in their environment. They ‘hear’ with a combination of their lateral line, swim bladder and their ‘otolith’ ear bones. As is the case with the hearing system in humans assisting with balance, a fish’s hearing system is similarly used for helping their orientation in the water. On top of that, it assists with their depth monitoring and navigation – handy when they live suspended in a three-dimensional environment.

They may not have ears as we know them, but trout can detect sound and vibration very well.

Trout exist as both predator and prey in the food chain, so sound can be either a source of attraction, or a warning. As flyfishers, we need to take advantage of the ‘attractive’ dinner-bell side of the equation, without crossing the line into the ‘danger’ side.

Pitch perfect

One potential positive, is we can use surface impact with our presentations to alert the fish to the fly. An obvious example of this is when fishing terrestrial dry flies like hoppers or beetles. In this case, the landing of the fly is a reasonable sonic copy of the natural insect landing on the water. The extent of this sound can be tuned by both the construction of the fly, and the cast. Hard-bodied flies, made from materials such as foam, will really enhance the percussive impact when the fly hits the water. Similarly, line speed and a downward trajectory of the cast can add to the intensity of the presentation.

Sound can be a critical ingredient for a hopper presentation.

There can be no doubting a trout’s sense of hearing when watching one turn and charge downstream to a hopper plopped down hard well behind it. Many times, I’ve seen fish come the full length of a Snowy Mountains pool, from the head to the tail, bow-waving towards a percussively-pitched hopper. That’s not to say this is the presentation we are looking for in all cases. For example, a fish racing downstream and facing the angler, brings all the consequences of hooking a fish facing you.

Nevertheless, this case demonstrates how it may be possible to use the trout’s sense of hearing to move it to a more desirable position from an angling perspective. Note that this can be applied to both dry fly and wet fly presentations. The goal is to get the fish’s attention and motivate it to investigate outside its current feeding zone.

Before going into specifics, it’s worth mentioning the overall influence of water dynamics in regard to background noise. Still water or smooth, gliding flows, generate less baseline/ background noise on streams than boisterous flows; likewise waves versus calm on lakes. This means less fly noise is needed in quiet water than ‘loud’ water to get the trout’s attention, and fish will move further to investigate in quiet water too. Water clarity is also something to think about. Discoloured water will still transmit sound, even if the visibility is poor, so hearing can take on increased importance over eyesight in these situations. This opens the door to fly rattles built into wet flies, or bulky water-pushing flies for ongoing noise attraction during the retrieve.

With all of this in mind, let’s look at some scenarios where we can use this to our advantage.

When it comes to trout on station, the textbook presentation is to deliver the fly drag-free, upstream from the fish, such that it drifts naturally through its feeding window. There are times, however where this isn’t possible. A fish may be holding in an ‘impossible’ lie, for example under a branch, or in another tricky position. The sound of a fly deliberately landed a little outside its visual feeding zone, can still bring it across for a look, and hopefully a take.

The sound of the fly landing is the only possible way of bringing this trout out for an eat.

Cruising fish in quiet water, like lakes and pools, can also be a prime target for ‘sound’ presentations. A fish might otherwise be out of casting range, or its beat may be so tight to a bank that any cast in its path might risk being hung up, or every time it shows, it’s already heading away so any attempt to cast in front of it will risk lining it. A fly deliberately presented away from the fish can, in these cases, bring the fish to where you want it.

This also raises another advantage of a deliberately off target sound-based presentation. Landing the fly too close to a fish can trigger its fear/warning response, instead of its predator response, resulting in a spook. Obviously, the objective is to put the fly where the fish will be able to locate it, but without scaring it.

In such bright, still conditions, casting ahead of this departing trout would almost certainly line it.

How far do we land the fly from the fish? The universal ‘it depends’ answer can be frustrating to hear, being influenced by all sorts of variables such as fish attitude (aggressive vs timid), water clarity, light intensity, primary food source at the time (say, hoppers vs mayfly) and so on. The truth is, lots of factors come into play. Experience, through both success and failure, will help teach you.

As an aside, it’s worth mentioning those slow-moving fish which will stop completely while facing a weed-bed or even open water. Are they watching or listening? I used to assume the former, but more and more now, I wonder if they are listening for prey.

Is this slow cruiser looking, listening, or both?

Bad vibrations

All this brings us to the need to discuss the negative side of sound. As touched on earlier, trout sit in the middle of the food chain, so they need to be aware of threats to them, as well as looking and ‘hearing’ for food. We, as humans, understand the instant alarm when someone sneaks up behind us and makes a loud noise. This survival response is built into all living creatures, and trout are no different. The favourite phrase of Isaac Walton, ‘Study to be Quiet’, is often well heeded.

Casting concerns

Plonking a fly, line or leader too heavily on top of, or close to, a trout will often result in an outright spook, or at best a heightened nervousness. Even an intentionally noisy presentation is usually best placed off to one side of a fish or behind it. And heavily landing a flyline too close is never good.

Another element where sound can cause problems, is a noisy lift-off to recast. This a fast, sudden rip of the flyline off the water into the back-cast, resulting in a loud ‘slurp’. If it’s audible to the angler, it’s definitely audible to a fish! An obvious consequence of this can be a spooked fish, but a more subtle problem can be a fish coming over to investigate the noise, thereby requiring a change of plans mid-cast. A noisy lift-off can be avoided by a slow initial lift or ‘slide’ into the back-cast, waiting until the flyline is off the water before accelerating into the back-cast.

In bright, still conditions, a soft landing of fly and line can be especially important.

Similarly, line splash on the delivery is usually bad. An attractive plonk or plop should be caused by the landing of the fly, not slam-dunking the whole delivery system, which probably sounds more like an attacking cormorant or other life-endangering predator.

Angler noise

Other problematic vibrations are created by angler movement, especially heavy steps or stumbling. The issue is most obvious when wading, but can be almost as bad on the bank. I’ve seen happily-feeding fish slink away in disgust after the heavy landing of an out-of-sight angler moving into position without ever touching the water. As for clumsy wading, recently, in New Zealand, Peter Hayes and I watched a trout on station from a bridge for 15 minutes, while an angler prepared to wade in from downstream and cast. This was on a large, quite boisterous river, and the angler was well outside the fish’s visual window. On their first step into the water, the angler stumbled on the slippery rocks. Peter and I looked straight back to the fish, and it was gone.

Keeping out of sight is only half the battle – you also have to keep out of sound, so to speak. 

This brings us to the somewhat contentious question of metallic wading boot studs or plates. My feeling is that these can absolutely cause noise that will spook fish. But it’s also true that you can’t catch a fish while lying in hospital, or worse. Safety is really important when wading. And if studs give you better grip, making you less likely to stumble, they may help with quieter overall wading. All I would say is that whatever boots you are wearing, try to keep wading sound to a minimum. Take your time and make as little commotion as possible while sneaking into position.

Boats are the other medium where angler actions can generate unwanted noise and vibrations. I’m generally a landlubber in my fishing, but everything I’ve been told by experienced boat anglers is that banging and crashing around in a boat works like a teenager practising on a drum kit. Not something that anyone or anything wants to hear!

Silence is golden?

A final topic is whether fish can hear anglers talking, and if so, does it affect them? I’ve watched quite a few YouTube videos recently, where GoPro cameras have been submerged to record underwater fishing action. People talking above the water can be heard quite clearly on the camera’s inbuilt microphone. So, I have no doubt that fish can hear voices above the water – at least in certain cases. Talking can be unavoidable, for example when a guide or other person is directing an angler onto a fish. Does it cause problems? I can’t actually say I’ve definitively seen a fish adversely react to talking. But all other things being equal, it probably doesn’t hurt to keep volume and unneeded yelling and shouting to a reasonable minimum.

There you have it, some pluses and minuses of sound in the trout’s world. While the visual nature of flyfishing may make sight the first priority, hopefully this article persuades you to pay more attention to sound – both to increase takes, and to reduce spooking or rejections.


Off Track – And your bug can sing

What the Duck – Can you speak fish?

What the Duck – Nature’s Vibrators