Every fisherman has wished they could dive underwater and see where the fish are, what the lake basin is shaped like, and where the drop offs are. But until you grow gills or become a scuba diver you will have to rely on the next best thing: lake maps.
Maps of lakes, or hydrographic maps, can be great tools for anglers. They show how the lake bottom is shaped by using contour lines at certain intervals, usually five- or ten- feet. An experience I had this winter is a good example of how useful a lake map can be. We put a fish house on a drop off and had some success with walleyes and smaller northerns. A lake map we had showed a small point near us that jutted out into deeper water. We used a depth finder, and in just a hour or so, found the underwater point. The first evening resulted in some small fish, plus two walleyes between three- and four- pounds. A few weeks later we decided to investigate another point on the map that extended out into deeper water in the middle of the lake. Again it took only a short time with a portable depth finder to find the precise spot. That move quickly resulted in several walleyes, with one weighing nearly seven- pounds.
Over 4,000 Minnesota lakes have been mapped since the early 1930′s. Crews with the Civilian Conservation Corps would chop holes in the ice at certain intervals and measure the depth with weighted lines. Later, in 1949, crews began using a fathometer, or echo-sounder. This was much faster and gave a continuous recording of the bottom as the boat moved along a predetermined line.
These finished maps are not only used by anglers, but help newcomers to safely navigate the lake and give fishery biologist a picture of the lake basin so they can manage the lake. Keep in mind that it is not feasible for mapping crews to make a completely accurate map of all lakes. Lake maps show only the general outline of a sunken island, reef, or drop off. If you investigate a structure closely with a depth finder you will usually find small points, fingers, inside turns, and all sorts of fish attracting spots not indicated on the maps. But the general information give on most maps gives you an idea of where to start.
I like to order maps before fishing a particular lake, while there is time to closely scrutinize each one and mark good looking spots. There are many commercial lake maps available in outdoor retailers, bait shops and online. My favorite source of lake maps is LakeMaster Lake Maps, 59 East Broadway, Little Falls, MN 56345…www.lakemap.com
Posted by Jeff Howard on May 20, 2011
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