Understanding the Unknown
I know this is the one area of study that can provide the greatest concern for almost every fly angler. This section of the class deals with the basic question of what really constitutes a fish's diet. This whole thing of needing to know just which imitation will produce the desired result, has frightened the day-lights out of almost everyone that gets deeply involved with this sport. You have already learned that a fish's diet consists of food items found at the bottom of the water column and that this bottom diet represents better than 80% of all food consumed by the fish. So, the question is, what the heck is down there and why is it so darn important for me to know and understand? There's no question that if you wish to be consistently successful, you'll have to achieve a working knowledge and understanding of the water columns environmental make-up and the various organisms that inhabit it.
Remember that fish are basically lazy when it comes to working for a meal. Fish will instinctively expend minimal energy in relationship to the amount of food that it can ingest. That's why we find these creatures lying in wait in areas that will provide a food source with minimal effort, such as riffles, current seams, inlets, eddies, flats, tails of pools and any pocket of reduced flow resistance that will create a feeding lane.
The key to unlocking this mystery is located in the water itself. In this watery environment, the fish holds the position of #1 in the food chain. Everything below the first position is fair game and will be considered a viable food source by the fish.
This column of water contains an abundant supply of potential food possibilities. The one area of the column that has the greatest potential for providing an easy meal is the bottom of the water column of rivers, streams, lakes and ponds. This area is literally crawling with aquatic insects that are in the larval or pupal stage of development, as well as, forage fish, shrimp, worms, leeches, crustaceans and a few dozen organisms that you just don't want to get involved with at this time. The largest of these food sources would be the other smaller fish, and yes, even the fish's own species is not exempt. The smallest food sources are the larval stages of the aquatic insects that we call Midges.
The bottom of the water column has the environmental characteristics necessary for a full range of aquatic life forms to exist. The soft mud and silt will allow many species to burrow, while others will develop into crawling and clinging characteristics or become busy building nets, cases and tubes in which the aquatic insect can protect itself while it grows into the next stage of becoming a pupae. Still others will be quite content to become free-swimming and hang around areas that have shelter and/or protection nearby. These aquatic insects will obtain their food by consuming microscopic life forms, organic materials and even roam the bottom of the water column looking for other smaller aquatic insect to ingest.
Most all species of aquatic insects have a one or two year life cycle and each insect is programmed by nature to develop and hatch at certain times or during certain environmental conditions. After months of growing into the adult nymphal stage, these creatures will then start to rise to the surface, break through the surface tension and emerge into the air-breathing world as adult flying insects such as: Horseflies, Deerflies, Craneflies, Mosquitoes, Blackflies, Mayflies, Caddisflies, Dragonflies, Damselflies and once again a few too many to really care about at this particular period of time.
Just in case you're interested, this list also contains just about any creature that is unfortunate enough to fall onto the surface of the water such as: Bees, Ants, Beetles, Wasps, Hellgrammites, Grasshoppers, Caterpillars and even some small animals and reptile. I could go on for a few more paragraphs but that will just make things unbearable and cause you to rethink attending any more classes.
The above mentioned abundant food sources are the focus of not only the fish but also the angler willing to take the time necessary to learn the importance of using this knowledge in order to select the correct imitation that will produce the desired results. The study of aquatic insects will give you this advantage and make you far more consistent and successful than most fly fishers.
We start the process of understanding by breaking this rather large list of creatures into three basic groups:
1. Swimming
2. Non-swimming
3. Terrestrials
The swimming group would include: other small fish, shrimp, free-swimming nymphs, leeches, amphibians and emerging pupae.
The Non-swimming group would include: crawling, clinging and burrowing nymphs, crustaceans, worms, and larval stages of aquatic insects.
The Terrestrials would include: bees, ants, beetles, wasps, hellgrammites, grasshoppers, caterpillars and any real small animal or reptile.
Now the big question is, which one do I use and when do I use it? This is where all the things that we've talked about come into play. Remember this phase, "750 + 3 is just for me", because this refers to the water temperature maintaining a consistent temperature for three consecutive days. Once this occurs, the aquatic insect community really starts to become very active and the first of many active hatches will take place. Remember that these hatches will basically follow a pattern of events. The first aquatic insects to hatch are the Midges. These insects will hatch almost year round as long as the water isn't iced over. The Stonefly has species that can hatch from early April to well into September. The more routine and familiar sequence of aquatic insect activity begins with the Mayfly hatches of April and May, which will give way to the Caddisfly, which will hatch in late spring and early summer. On rocky rivers and streams with cool, oxygenated waters the Stonefly will actively hatch throughout this same period. Then in places that have aquatic vegetation the Dragonflies and Damselflies will hatch actively. As the summer heat brings the water temperature up to an uncomfortable range, the fish will seek cooler waters and change their feeding habits. These cooler waters are found near spring holes, deeper pools, inlet areas, the tail sections of the shallower pools and any shaded areas of the body of water.
The following is a little lesson to help decide what imitation might produce for you. That all important question of, "what will I use and how do I know when to use it." Fishing is very much like hunting, in that, you are looking for something to catch. Like hunting, you will match strategies based on observed environmental conditions.
Scanning For Fish
S= Season, Month, and Water Temperature (Spring, Summer, Fall and Winter)
C= Clarity and the Color of water (Transparent, Green, Blue, Amber and Brown)
A= Above or Below surface activity ( Dry Fly, Emerger or Wet Fly )
N= Nomenclature of the imitation Terrestrial, Dun or Spinner, Wet or Nymph