Fishing for trout with a flyrod this time of year can be both challenging and rewarding. The lack of snow this winter has kept the streams relatively low this spring. There are hundreds of streams throughout New England that are just teeming with fish. And, if you are there at just the right time with the right fly and the right technique, you can fill the frying pan with some tasty fare.
Trout feed on insects. The insects come in an amazing array of sizes, colors and shapes. They all also go through many life phases often all within a very short period of time in a small stretch of water. Understanding this life cycle will help you figure out what fly to use under what circumstance.
As with any explanation of nature there are odd variations of almost everything, but there are also some general truths that work well most of the time. As we start we work off the generalizations and then, as we get more sophisticated in the art, we recognize and deal with the exceptions
In most streams, the larval form of insects represent a large part of a trout's diet. In his terrific book entitled"Nympths", Ernest Schwiebert suggested that anywhere beteeen 75 and 95 percent of the total food consumption of a trout are nymphs. Because of that, it is important to a fisherman to recognize what is being consumed on that day. It's shape, size, color and habit of movement are all keys to "matching the hatch."
For example, the Blue-Winged Olive fly overlaps with hatches of Hendricksons later this month on most New England streams and is wonderfully prolific. Fishermen with a few of each in their box can often bring to the creel some nice trout, land-locked salmon and even bass.
There are many different species of this mayfly with hatches emerging from moving water all through the winter and early spring. Their nymphs live in almost any running stream, but they prefer slow or moderate runs. Once they change from the nymphal stage and struggle to the surface as a fly, they often drift lazily along on the current into back eddies where they will swirl around until some enterprising fish slurps them down.
To really know how to fish these flies, it is important to understand their life cycle. The eggs in the water hatch anywhere from one to four weeks after they have been laid. They stay on the bottom of the stream over the next few months preferring to live in gravel or rubble. There they eat microscopic aquatic alga and vegetation. They grow larger over time in a series of stages called instars. At the end of each instar, they molt the shell that holds them and they develop a new one. After about ten instars they grow gills and at about fifteen instars they grow cases that protect their growing wings.
These mayflies will go through as many as thirty molts in the nymphal stage. Once they have reached their nymphal maturity, they struggle to the surface and shed their skin. This new creature is called a dun. It sort of sits and dries out, recovering from as much as a year in the confines of its nymph suit.
Although they can emerge almost anytime, they seem to be most active in the early afternoon. And, unlike a lot of insects that make the stream beds their home, these flies seem to like to emerge in the rain. They shed their last skin and emerge as a fly. They crawl up on a leaf or rock and rest. Within a few hours they change in coloration a bit and become what is known as a spinner. Late in the afternoon or evening of the same day they struggle up out of the water, the females fly into a swarm of males where their eggs are fertilized. They then dip to the surface of the water and lay their eggs. Some females will even crawl or dive into the water to release their eggs. They soon after fall to the surface of the water and die. All that effort of molting gone in one afternoon above the waters surface.
Fish will feed on these insects at all levels of their development. They will pick up the nymph along the bottom if they are disturbed by some movement of the water; a spring freshet, a rain storm, a water release from a dam, etc. Often the nymphs will move from their hiding spot in the gravel when they grow larger through a molt. They are surprisingly agile in the water. Of course once they start up from the bottom in a hatch, the fish will feed on them as they struggle to the surface and then feed on the duns and spinners that fall onto the water surface from above.
On a beautiful warm day when there is no wind to ripple the surface, fish can be very selective. They will often feed on only a size and/or color that really matches the hatch. Spend a little time on the stream with a fine net and examine what is floating in and on the water. Although the flies can be of the same family, coloration can vary depending on the stream. Also watch the feeding fish. If they are staying active down in the water column, they are often feeding on the nymphs. Later in the day they will often feed on the surface as the adult flies drop back to the surface to lay eggs or die.
The prepared fisherman will have several nymph patterns of different sizes, a dun pattern that while look like the fly emerging from molt, and will have a spinner dry fly to imitate the fly that drops back to the surface to die. The wet fly that works quite well would be the Pheasant Tail Nymph and the Gold Ribbed Hare's Ear nymphs. I like to use a gold beaded variation of these two. It keeps the fly down low along the gravel and the bead is a bit of an attractor. Try a parachute version of the Blue-Winged Olive for the dry fly. It floats really well.
This time of year there is a lot of insect activity in our rivers. I love to fish a Pheasant Tail Nymph as a dropper behind a stonefly in moving water that flows over gravel bed streams. I fix a strike indicator up the line and try to float this combination as naturally as possible through the pool. When that strike indicator even hesitates, pick up on the line. Sometimes you will be fooled, but feeding fish often just inhale these small flies as they drift by. They do not slash with great energy. Once in their mouth, if the fly doesn't feel natural, the fish will spit it out. Therefore, just a bit of hesitation may indicate a strike. Set the hook!