Tips for Selective Trout...
To understand selective trout, it is important to first understand a little about a trout's vision, and how it views its surrounding environment and how it identifies "food" and ultimately eats it. Then, it is helpful to understand "selective behavior" in trout. As trout fishermen, we all spend a lot of time and energy trying to "match the hatch". Why do we do this?...to catch more and perhaps larger fish. If trout did not display selective feeding behavior, there would be little or no need to "match the hatch". Finally, we have to learn and employ techniques that help us get our fly to the fish as "naturally" as possible without disturbing the fish with unnatural "drag", a bad cast or just being a too obvious presence to the trout. Even armed with all of this knowledge, I think the trout still has the upper hand but you will have increased your odds. Personally, it is the selective nature of trout that has made fly fishing such a joy for me. If I caught every trout I cast to, I would find something else to chase...
When we talk about "selective trout", most of us think of dry fly fishing. I have also done quite a lot of fishing small nymphs in my pursuit of highly selective trout. The two places that automatically come to mind are the Henry's Fork and Silver Creek in Idaho. I have also spent many days on other slow and meandering spring creeks across the West. I have learned through countless hours and days of frustration that, when fishing small and generally unweighted nymphs to selective trout, presentation is no less important than if a dry fly was tied to the end of that 6X-7X tippet. I usually fish these small (#16-#20) nymphs just as I would a dry fly and trying to keep it in or just under the surface film. I have spent hours "bank sitting" with binoculars watching fish eat naturals and quickly realized that all rise forms are not the same. I wondered why and have been a bit of a student on this topic for years.
Most of what follows is directed to the dry fly as that has always been my primary focus when I have had a fly rod in my hand. Just also be aware that a small nymph fished just under the surface film is nearly as effective as a dry fly even during steady hatches and rising fish.
To understand why a trout will take one fly and not the next and assuming the flies are identical, means you also need to understand what a trout sees and does not see and the various factors involved in the trout's decision to eat a fly. Some of the earliest serious work on this subject was done by Vincent C Marinaro in his classic book "In the Ring of the Rise" .Published in 1976, it provides the fly fisher with an excellent analysis of various trout rise forms of feeding trout and provides us with some of the first real data on how and what a trout sees. In the book, the author describes in detail "the actions of a trout rising to an insect. Page after page of sharp, detailed photographs show all the stages of a trout's rise, and the photographs of the trout's view of a fly moving into its field of vision are unequaled."
In the process of digging around for more information on a trout's vision, I ran across an interesting video/animation that is based on some of Marinaro's work. This video will help you understand how a trout sees its food and decides what and when to eat. The title is "How Does a Trout Catch a Fly?: Marinaro's "Edge of the Window Theory" Watch the video here... Also, there is discussion on this topic in the lower portion of the same page.
For some time, I have been following "The Fly Fishing Forum" As I recall, this forum gets over 7,000 visits a day and I believe this is by far the most active fly fishing forum on the net. It is free to join and has great information and discussions on just about anything fly fishing related. A couple of months ago while working on another article, I ran across a post by a forum member who goes by the moniker "silver creek". He is evidently a retired physician and chemist. As it turns out, he is best friends with and was taught to fly fish by Gary Borger. I came across one of his posts titled "Selectivity - why and how do trout become selective feeders" . It is a rather long post and does an excellent job of talking about how and why trout become selective. This post really helped explain things I have wondered about for many years.
Early in the article he makes the following comment ands asks a good question: "The underlying principle behind matching the hatch is selectivity as a feeding behavior. What is it and why does it occur? Why do fish sometime eat sticks and hit strike indicators, and at other times will ignore a well presented fly that imitates the current hatch?" He the lists four (4) rules...scientific principles really and they are:
1. The first rule is that any behavior is population based.
2. The second rule is that selectivity is a survival mechanism and is not based on intelligence.
3. The third rule is that selectivity can only occur in fertile watersheds.
4. The fourth rule is that larger fish must become more selective than smaller fish if they are to survive.
He then goes on to discuss these principles in detail and provides several "graphics" to better explain his thoughts. I assure you that if you read this post (see link above), you will learn something about selective trout behavior.
Once we have a general understanding of how and what a trout sees and learn a little more about "selective behavior"...neither of which we have any control over, we have to learn and employ tactics and strategies to increase our odds of successfully catching selective trout...or other fish for that matter. I am specifically talking about the all important presentation that include things such as:
Positioning - are you in the best place to cast?
Gear - Is your line, leader and tippet appropriate for the situation?
Managing "drag" - use different "presentation" casts and mending techniques.
Fly selection - choosing the right fly.