'Triggers'

[Silver Creek]

No! Not the horse. The term that many fly tiers use to bolster their claim about a fly pattern or design that they have 'invented' (or whatever word you want to use) and causes the trout to hit that particular fly pattern.

Now, do trout strike because: of 'triggers'; the 'impression' of the fly; the 'imitative' likeliness of the fly; the 'presentation'; color; size; shape; All of the above. None of the above. Some of the above?

Why is it that at the same location, on the same river, on two succeeding days with almost the identical weather pattern and river conditions, at the same time, same hatch, same flies, etc. you have great success and then get skunked?

I'd really like to hear if anyone really thinks that a particular 'something' works as a trigger. And if it does, why does it not work all the time. And lastly, if you're that sure about 'that 'trigger', then there's only 1 reason to have flies that are another design - you don't really have that much faith in that 'trigger' now do you?

Sorry, but this is a subject I'm always interested in and have found it interesting to discuss, especially with fly fishers who strongly agree with the concept yet, have several hundred or more flies in their vest.

All the above written in good humor and opinions are just that.

Allan

Allan,

A member of this forum asked me to repost here, a post I made on another forum about how trout become selective feeders. The questions you are asking, for the most part are answered in the post below. You are basically asking why trout will at one time or in fact at one location with the same flies/hatch hit a particular fly and at another time not.

The thing to remember is that trout are biologic organisms whose behavior is population based. Given a smorgasbord of food, not everyone on this forum would eat the same food, or in the same order, or in the same amount. And yet we seem surprised when trout that were hitting a fly one day will not on another. Although you say that the weather was the same, the flies were the same, and the time of day was the same, the behavior was NOT the same.

My answer is that there had to be parameters that were not the same. When you read the post below, one possibility is that the fish where you were fishing were more selective and the fly and presentation that worked when the fish were less selective did not work with a population of fish that became more selective. The longer a hatch goes on and the denser the hatch, there is increasing probability of selective behavior for the reasons I explain in my main post.

Another possibility is a masking hatch. Could there have been an event such a flying ants that was totally unexpected. Ants are extremely hard for an angler to detect and I have been fooled by them more than once. This happened to me just a few weeks ago on the Madison River when a fly that should have worked did not. There were size 22 flying ants in the drift.

The term trigger in fly fishing to me means an attribute of the fly, without which the fish will not hit the fly. It may not even be how the fly looks. It can be the water column that the fly seeks, or the angle in that water column that the fly naturally assumes. It is something about the fly that causes the fish to "pull the trigger."

With the introduction above here is my post on "How Trout Become Selective Feeders".

Part 1:

Please forgive me for this long post. I have posted on this subject on other BBs and I have found that most fly fishers do not understand the biologic basis of selectivity or matching the hatch.

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?

There are several principles that need to be understood.

The first rule is that any behavior is population based. What I mean by that is that when we are fly fishing, it is our nature to assume that the behavior we see is the behavior of all the fish. It is not. Just because one fish takes a fly or refuses a fly, we cannot assume that all the fish will do the same thing.

In fact, the behavior we observe may be an atypical one. This is called sampling error. When we fish, we are sampling the populations for those fish that are susceptible to the method we are using; and therefore, any success we have is based solely on statistical variation. We are more likely to be successful when using a method that targets a greater proportion of the population, but we often forget that fishing is a statistical sampling method.

The second rule is that selectivity is a survival mechanism and is not based on intelligence.

The third rule is that selectivity can only occur in fertile watersheds.

The fourth rule is that larger fish must become more selective than smaller fish if they are to survive.

So with those principle in mind, here is my view of selectivity.

Selectivity occurs only in situations where there is abundant food. If the fish live in a stream where food is scarce, they will feed opportunistically. They cannot be selective to just a single food source because there is never a large or sustained hatch to become selective. So selective feeding occurs only in nutrient rich environments.

Selectivity is the most efficient method of feeding. An organism can only survive if the energy it gets from food is greater than the energy it expends to catch and eat the food. Selectivity then is a biologic necessary method that optimizes survival. It is a biologic adaptation that gives the organism that uses it a survival advantage. That is the reason that the fish feed selectively. They cannot help themselves from becoming selective feeders.

Another biological cause of selectivity is the size and age of the fish. As fish grow older and larger, their energy (calorie) requirements become relatively greater. A large fish requires more energy to chase food and yet gains fewer calories per body weight when it eats the food. Because larger fish expend relatively greater energy to catch food, but receives relatively less energy when it captures food; it must feed effectively if it is to survive. What is crucial then is not the total number of calories in a food item, it is the ratio of the calories spent vs the calories consumed per body weight.

For large fish, selectivity is more important as a survival strategy than for smaller fish. That is why we see smaller fish chasing food and our flies but rarely do large fish chase a fly unless it is a large fly that promises a large reward in calories.

Once a fish feeds selectively, it cannot help itself from feeding on our fly, if the fly meets the criteria for food.

How then does a fish become selectivity? Well, they don't do it through intelligence. Trout cannot reason. What trout can do is sample; they sample what they think is food. If the item is food and it is abundant enough, the trout will feed on it often enough that the visual pattern of the food eventually becomes imprinted. Then the fish then begins to search for this food pattern exclusively and ignores most other items that could also be food. If the food is very abundant, the fish will begin to both narrow the area it searches ( the fish feeds only on food that is in a narrow "feeding" lane) and the fish will develop a feeding rhythm. The fish mechanically moves up and down, taking the food item that happens to be in its feeding window.

The psychologist term for the development of selectivity is Operant Conditioning, Operant conditioning - Wikipedia, the free encyclopedia as first described by B. F. Skinner. The fish is rewarded when it feeds on an item that is food and if there is enough of this particular item, the fish becomes conditioned to feed only on that food. That conditioning is what we call selectivity.

The fish does not reason, it takes whatever is in the window that meets its search pattern. It is all automatic and the fish cannot help itself from taking our fly if it meets the search pattern, and it is in the right place (feeding lane) at the right time (rhythm).

The question then becomes, what are the fishes search criteria (triggers)? Everyone seems to agree that size, shape, behavior and color are search criteria. We know this, not because of positive evidence, but because when the fly does not meet all or most of these criteria, the selective fish refuses to take the pattern when it is in the right place at the right time.