Not every river you fish will feature endless arrays of perfect pockets, pools, seams and structure in which to easily locate fish. Sometimes, we have to find fish in water that has less distinct characteristics. Rather than waste time blindly casting to empty water, possibly putting down fish with our efforts, stop and take time to observe the surface characteristics of the flow.
Laminar flow can be the most enigmatic water to decipher. It is water that flows at an even speed from top to bottom bank to bank. I normally walk by water that exhibits no obvious structure in which to target my effort. Smooth even currents from bank to bank merely bumping over the rubble is akin to fishing on the moon. I know fish are present, often seeing rises out in the nondescript waterscape, but fishing this water requires more time and effort than casting to fish around obvious structure.
If you do chance upon a feeding fish in a section of river that is laminar in structure, spend some time observing where that fish is located. Even without the telltale signs of current seams, the location of drifting insects and fish are not left to chance. There is a structure at work that the fish use to thier advantage.
Fish will use whatever structure is available to them within the limited confines of a river. Sometimes we must look at less than obvious structures in the laminar sections of water. When looking at laminar flow, observe the structure of the river bottom and speed of the current. If the substrate consists of only sand, silt or very small cobble, with a flow that is walking speed or faster, you are better served moving along in search of something else. However, if you find laminar walking speed flow with a substrate that consists of bowling ball sized cobble you are in luck. You have found water that may contain fish. Small boulders create micro vortices that can hold a fish in the current, so the fish spends very little effort in maintaining its position. Deschutes River steelheaders know this when they fish those classic named mile long runs.
Before you wade into the river and start casting with the usual routine of starting in close working your way out in a clockwork shotgun fashion, take time to look at the surface of the water and try and find the “lanes” that do exist. Lanes are the micro seams that slip past each other funneling everything that drifts downstream into narrow bands. The best way to find the lanes is to find the bubbles. Are the bubbles accumulating in a concentrated area? If so you have found your lane. It may take some time to train your eye to look for a higher concentration of bubbles gathering in an inch wide seam amidst an even dispersion of bubbles, but when you do, you have found your area of concentrated effort. Fish will be located within close proximity of these micro seams in order to easily slip away from thier vortex and inspect a likely morsel.
In the images above, I have used the tools of photography to illustrate where micro seams actually occur. In figure 1, we see a general random dispersion of bubbles on the surface in a section of laminar flow over bowling ball sized substrate. In figure 2, I exposed the image longer to blur the lines and now you can see the micro lanes as faint white stripes, so that you will know better where to concentrate your efforts.