Reading a stream enables an angler to find fish by skill, not chance. It can also be argued that nowhere is reading more important than in springtime trout waters. There are many varied water types: riffles, runs, pocket water, pools, rapids, cascades and frog water, but most of the trout, at this time of year, will be caught in one of the first three. Thus, we will concentrate on identifying and successfully fishing riffles, runs and pocket water.
THE TROUT’S NEEDS
Trout require protection, food, oxygen and proper water temperature. They seek protection from predators, shun sunshine, and they burn too many calories in heavy currents. Because of their awakening metabolism in the spring, trout require a constant source of protein to fuel their bodies after eating sparingly all winter.
Since oxygen saturation varies between areas of any river, they seek high oxygen content areas. Trout also move to areas where the water temperature fits their biological needs. Too cold and the insects and minnows (the trout’s common food sources) will not be active and accessible. Too warm and the trout will become uncomfortable.
The shallow areas of the stream, where bottom features cause choppy or mildly broken surface water, are typically called riffles. This can include anything from “nervous water” to some light white water, and may be from 3 inches to 3 feet in depth. Because of its shallow nature, the bottom structure of riffle water receives enough sunlight to generate considerable algae and aquatic plant growth. Riffle water is also well oxygenated. This is good news to the trout, as the plant growth encourages and supports a large insect population, which in turn feeds a lot of trout. Thus it behooves fish to move into the riffles to feed. However, the shallow nature of the riffles offers poor protection from predators, and trout often move out of the riffles to rest in deeper water, then return to them morning and evening to feed. Midday temperatures coupled with the high overhead sunshine will force the trout out of the riffles and back to deeper holds. When fishing the riffles, cast to every part of the water that appears to be over 6 inches deep. Look for calm zones and slicks within the choppy water and work these with extra diligence.
Many of the insects that live in the weedy growth of rivers will be knocked loose from their grip on bottom rocks or weeds and float down the riffles until located and eaten by feeding trout. Also, some minnows move into the riffles to feed on these bugs, only to become trout treats themselves. This enticing supply of food draws even the large wary trout into the shallows to feed when the sun is off the water and shadows offer some protection.
As a riffle deepens downstream, it becomes a run. Runs are waters varying from mid-depth to pool deep. They are characterized by smooth surfaces broken only by current seams created by large rocks, river bends, fallen trees and ledges. Runs are excellent trout retreats. Their shallower waters, just below the riffle, contain some plant and insect growth, while their deeper flows farther downstream offer large trout the protection they desire. As the riffle tails out into a run, a dropoff or ledge is often found. This is a great place for feeding fish to hold. Trout will nose up to the deep side of the ledge and wait for insects to be washed out of the riffle and over the ledge. Concentrate your fishing time on these ledge lines, casting into the shallow flow above and allowing your bait, fly or lure to tumble over the rim.
Look for current seams, those areas where slow current abuts faster flows. Trout will hold on the slower side of these transition zones while watching for insects carried by the faster flows. Seam lines and the bubble lines they often create are trout smorgasbords, delivering a variety of tempting morsels. River bends will often produce undercut banks on the outer side of the flow. The largest trout will often claim these protected cuts as their main address.
Runs with silted structure-less bottoms hold few fish; however, if the silted bottom harbors good weed growth, then trout will root in the weeds to dislodge the bugs that live there. If the banks along a run contain grasses, bushes or trees that grow up to or hang over the water, trout will hold along these woody shores picking off the terrestrial insects that live in the foliage. Terrestrials, like grasshoppers, crickets, ants and beetles are a constant source of trout food as they fall or are blown onto the stream.
Pocket water areas are those places where water cascades into frothy vanilla swirls; rock gardens where the flow breaks around boulders, crashes into intersecting currents and eddies into tiny glass-topped pools (pockets). Pocket water can be defined as any run marked by fast water, deeper and more varied than riffles, where rocks of sufficient size break or bulge the surface, creating varied currents and tiny pools. The pockets represent tiny rest stops, providing trout a comfortable habitat in water otherwise too fast and heavy to hold fish. Rough-water pockets hold fish, lots of fish, and contrary to popular opinion, they hold many of the stream’s largest trout.
What you should look for are the places in fast-moving water where the current abruptly changes flow-rate. Any object in the water is going to affect the current in some manner. Large and small boulders and rocks, dips and holes in the streambed, bank protrusions or logs and fallen trees all tend to alter flow-rates. To conserve energy, fish will look for the slowest water they can find next to a fast-water feeding lane. The best of these feeding lanes are seams created by conflicting currents. If there is deep water nearby these converging flows, you have the makings of a hold where the bigger fish call home.
A boulder in the water causes several different conditions around it. A large rock in fast water cushions the flow, creating a small slack-water holding lie in front (a front cushion). It splits the current, and friction against the rock slows the flow on either side (side seams). It breaks the current causing a pocket behind the rock (rear pocket) and slower flows below the pocket (slicks). Thus a trout might find a place to lie in that is directly in front of the rock, along the sides, in the pocket behind, and in the slower current behind the back pocket. Slack currents surrounded by intertwining food lanes are great spots for trout. The currents deliver the food, and the more convergent the currents, the more food delivered to this spot, thus the largest trout will be stationed there.