Have you ever thought that fish use the water for everything? If they're not hiding behind boulders, they're darting out into the current to grab a tasty bug or worm before it floats by. Most of the time, though, they are looking for a “lie,” or position, that combines safety and protection from predators and a steady stream of food. These “food alleys” are often found on the lee side of boulders and at crosscurrents. Here the fish can expend minimum effort for maximum gain.
Knowing where the fish are feeding comes from learning basic skills in reading the water. Rivers and streams have different depths, rocks both submerged and protruding, overhanging brush, weed beds, logs, debris, even temperature changes. These all provide clues about where fish are likely to be. Consistently successful anglers remain flexible from cast to cast in determining what flies to cast as well as where the fish are taking them.
In fast-moving currents (riffles), rocks help break up the current's flow. The oxygen-rich turbulence around rocks provides ample food. Fish hang out both in front of large rocks as the current veers around them and behind, where the water is still and food can accumulate. Around boulders and rocks it's more important that your flies are large enough and float well than that they exactly match real insects.
Areas between calm and faster water develop pronounced current edges, which anglers call seams. The faster water is also broken water—that is, the surface of the water is not smooth. That gives the fish a certain amount of protection from their enemies.
Salmonids (salmon and trout) prefer fast-water runs, so riffles are good places to fish. Others are:
Overhanging brush and trees draw fish because grasshoppers and other terrestrials drop into the water after a stiff breeze or gust of wind. These provide tasty meals for the underwater denizens. Aquatic insects, after hatching, often take to nearby brush before mating over the water. The trout seem to know this and wait patiently for female insects to hover above the water, dip to the surface to deposit their eggs, then collapse. These dead insects cover the water's surface ready for the hungry mouths of waiting trout.
A typical river may have only three different types of insects hatching, but those three types may comprise as many as ten to fifteen different species each. Thankfully, an exact match isn't necessary. All you need do is look in the surrounding brush and along the shallows to see what's flying around. Look for the type of insect and color first. Other areas of interest to anglers are weed beds, especially those in spring creeks. Crustaceans and insects breed here, and fish find ample protection from predators.
Lies, or fish haunts, are deep water, undercut banks, and log jams. These provide relief from swift currents and shelter for fish, which seek out these areas when hooked. Deep water and broken surface water offer protection, and rocky bottoms reduce the force of the currents. Trout tend to hold at the upstream edges of pockets and watch for food drifting in the currents.
During an insect hatch, or at other times when large amounts of food are adrift, fish move into feeding lies. These are usually found in shallow water, the tail of a pool, and the shallows near the banks. If you're patient and the fish don't see you (especially in clear water), you'll likely be rewarded when the fish move to these areas for food.
The confluence of two currents is also host to food organisms, and provide excellent feeding areas for trout. Two streams joining into one create a confusion of upwelling, plunging, and crosscurrents that scatter jumbled food.
When fishing streams and rivers, try to cover all of the water. Carefully fish every likely spot. Cast your streamer downstream near rocks, logs, and undercut banks, places that hold trout. Cast your weighted nymphs upstream, letting them swing down with the current and bounce over the bottom. If that doesn't work, try fishing wet flies across- and downstream, perhaps with two or three patterns on the leader so the fish have a wider choice.
Lakes are not much different from pools. If there is no insect activity taking place on the surface, trout will usually stay out of sight in the deep, sheltering water. Flooded trees offer them shelter. Since lake water doesn't move that much, trout move around in search of food. This means you need to be attuned to the feeding lanes, which can be close to shelter and anywhere shallow water steeply drops off to deep water.
Trout also linger near channels where streams enter or leave the lake, edges of gravel bars, drop-offs, deadfalls, dams, and islands. Don't pass up a chance to work a fly around weed beds, the food and oxygen manufacturing centers of the lake. Trout move in to the shoreline toward dusk, and on windy days, when food is blown near the shore. If not spooked, trout will work close in.
Warm-water species of fish such as bass, pike, and walleye have the same patterns as cold-water fish like trout. A distinct difference, however, is their diet. Walleyes and bass feed largely on minnows and crayfish and move to feeding lies when these prey organisms are most active—usually from late evening until just after dawn. Schools of panfish like bluegills and crappies follow similar patterns.
In lakes, warm-water species will cruise in search of food, wandering in and out of weed beds, over sunken weeds, along cliffs and flooded timber, and around islands and places where shallow water drops off into deeper water. Here food, oxygen, and protection are most readily available and most suited to the murky inhabitants.
Knowing how to read lakes and cast for fish in them can be daunting, especially if the lake is large and unfamiliar to you. Early in the season look for shallow areas in sheltered bays, where the sun can warm the water and draw aquatic insects. Mid-season, check out bays where a breeze rippling the surface first brings food, then fish. The breeze breaks up the surface of the water, and the fish feel secure. You have a good chance of finding fish where shoreline trees hang over a shoal, or area of shallow water, where a hatch is likely to take place. Even better—the trees provide shade that shelters the fish.
It's easier to read the bottoms of streams and rivers. Lakes are a little more difficult. When fishing a lake, especially in a boat, you might want to use a depth finder—not to find fish but to determine the slope and consistency of the lake bottom. You could work a nymph along a weed bed beside a ledge, or heave a streamer along the gradual slope of a rocky ledge at the end of a bay, where the wind concentrates food. In the middle of the day, work the deeper parts of the water column. At dawn and at dusk, fish the more shallow levels and even the surface.