Rivers

The other water type to consider in angling is the river. Rivers are systems. The environmental characteristics and fish species of rivers often change dramatically from the headwaters to the mouth. For river classification purposes, we can use the simplified aging process used for lake classification. The major difference, however, is currents. The continuous current in rivers has a profound influence on the environmental factors which control fish behavior.

The classic river system contains young, middle-aged, and mature sections. When present in the system, the young river section is always found at the headwater of a river system. Western mountain streams usually fall into this category. Low fertility, clear water, strong currents, high oxygen levels, steep banks, a relatively straight course, and few pounds of fish per mile are the characteristics of these rivers and streams. These waters are the usual domain of cold-water species.

Middle-aged river sections are always downstream from young headwater sections. These rivers usually flow more slowly and meander more often. The gradient and banks of these flowages slope more gently. A more organic bottom content often promotes weed growth and higher fertility. Less-than-clear water and gentler current are signs of lower oxygen levels and warmer waters. The middle-aged river is usually occupied by cool-water fish although the warm-water species may do well in the warm, shallow bays and backwaters.

As a river matures from the middle-aged stage the signs of aging become more dramatic. The gradient decreases to the point where current may be almost imperceptible. The river broadens and gets shallower and starts to twist and turn in a series of oxbows. Water temperatures are very warm and the water usually anything but clear. Mature rivers often provide an environment too stressful for anything but the warm-water fish community.

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