This is Maps 101. An understanding of the basics of not only what you find on the paper, but also how you need to interpret it with an understanding of the type of fish you’re after.
Maps, particularly those designed for anglers, present a great deal of information. First, maps are oriented directionally. They have a compass rose or north arrow showing both true and magnetic north. You can turn the map so it faces the same direction the lake faces. Positioning a map correctly helps you catch fish. You can relate lake features to predict the effects of sunlight and wind direction, as well as simplify navigation.
All maps are drawn proportionally or scaled. It’s not feasible to provide a life-size drawing, so a selected length on the map represents an actual distance on the lake. Each map uses its own scale because sizes of mapped areas differ. Anglers can determine the distance from one “hot spot” to another using the map’s scale.
Maps have limited space, so symbols represent a variety of features. The map legend defines these symbols, which may include; creek channels, weeds, man-made fish attractors, boat landings, flooded timber and navigation hazards to name but a few.
A significant feature of fishing maps is depth measurement or contour lines. Fish rarely inhabit the surface. They spend most of their lives well below the surface. Reading and understanding contour lines are the two most important skills in finding fish.
Depending on the size and scale of the map, contour lines can represent 2-foot intervals (the spaces between lines) up to 40 feet or more. A series of closely spaced contours represent a sharp drop-off, while widely spaced lines illustrate a gradual slope. Keep in mind that because of the scale of the map, those lines on the paper, in the real world, could be 100 feet wide! Many times those subtle changes in the bottom won’t show up on a map. That’s where time on the water and using your electronics come in handy. More about that later.
No matter what kind of angler you are, novice to pro, the common thread for success is a map. During the 20th century, America began impounding rivers and streams to create huge reservoirs and flowages. Topographical maps from the United States Geological Survey (USGS) done prior to flooding an area became the basis for many lake maps once the reservoirs were full.
While these maps depict considerable detail, they show contour lines as land elevations and not as water depths. Anglers had to mentally convert elevations to depths. Translating topographical land maps into underwater (hydrographic) contour maps also runs into another problem. Printed maps are based on a single water level. That is, they show a reservoir at a specific lake or pool elevation. If water levels rise due to spring runoff, or drop during a drought, maps don’t compensate for the variation. An impoundment map must identify an existing or normal pool level as its basis, so anglers can then project possible depth changes based on the higher or lower water levels.
Highly detailed pre-impoundment land surveys by the Army Corps of Engineers were also done. These maps not only showed contours but also depicted buildings, roadbeds, railroad grades, fence lines as well as areas where flooded timber was left standing.
The fishing map itself has a very short history. Anglers didn’t begin using fishing maps until the early 1960s – coincidental with the introduction of electronic depthfinders. Suddenly, a whole new world of electronic and cartographic information changed fishing into a science. Once anglers could coordinate their fishing with depthfinder data, they could mark their map accordingly and the fishing map was born.
Continue to Part II
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