How to Read a Contour Map for Fishing

May 1, 2017

The amount of fishing gear available to anglers today is larger than ever before. And granted, the advancements made in gear may help put a fish or two in the boat more often, but one of the most important aspects of catching more fish is understanding where to find them. A great place to begin is with a contour map that shows you the depths of the waterway you’re fishing on. How you interpret these wavy lines on the map can put you in the right spots, at the right time, more often than not.

Here are some tips to get you started:

Visualizing Changes in Depth
Besides the displayed gradient depths (usually marked in 5-10 ft. intervals), the space between contour lines is the key to understanding how shallow or deep you are fishing. Contour lines spaced narrowly between one another indicate areas of steep transition - meaning the depth of the water column changes from shallow to deep (or vice versa) quickly within a short distance. You’ll often hear anglers talk about fishing “drop-offs” or “points” when targeting certain species of fish - they’re referring to these same closely-spaced contour line areas on a fishing map.

Example of drop-offs located on a Fishidy map.
Example of drop-offs located on a Fishidy map.

On the other hand, when you see contour lines spaced far apart, it’s just the opposite. These are areas of gradual transition where the depth of the water column is changing from shallow to deep (or vice versa) slowly over a long distance. Anglers who talk about fishing the “flats” or “shallow” are referring to these same areas on a fishing map with contour lines spaced widely apart.

Example of flats located on a Fishidy map.
Example of flats located on a Fishidy map.

Understanding Behavior and Habitat
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Once you’ve mastered how to interpret changes in depth on your map, the next step is understanding the behavior and prefered habitat of the species of fish you’re trying to catch. Coldwater and warmwater species of fish have different preferences that dictate when they move, where they move, and for how long they’ll be there. These behaviors are often influenced by a variety of factors including light, weather, water temperature, food sources, and reproduction. Oftentimes fish behavior is closely aligned with underwater habitat or structure, and this is where your knowledge of depth comes into play.

For example, if you’re targeting largemouth bassin early spring, you’ll most likely want to seek out shallow areas containing emerging weeds and vegetation. For crappie in the middle of the summer, you’ll most likely start your approach in deep water basins alongside drop-offs, or on offshore flats with structure such as flooded timber or artificial fish cribs. The better you understand the fish you’re targeting, the more you’ll know what to look for on a fishing map with contour lines.

Focusing on Fishing Hot Spots
The last step in this process is wrapping together what you know from both of the previous steps, and keying in on the specific areas on your waterway where depth, structure, and fish behavior all intersect. Fish migrate on specific travel routes within the course of a given season. Once you have the knowledge of where these areas exist, and you’re able to identify these "fishing hot spots" on your map, you will drastically increase your chances of catching more (and maybe bigger) fish more often.

Access fishing hot spots as a premium subscriber on Fishidy.
Access fishing hot spots as a premium subscriber on Fishidy.

Hopefully these tips will help the next time you’re looking at a fishing map. Best of luck with your next on-the-water adventure.

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