Skip to content


Your cart is empty

Article: How to Use Sonar and GPS for Effective Tuna Fishing

How to Use Sonar and GPS for Effective Tuna Fishing

How to Use Sonar and GPS for Effective Tuna Fishing


Modern technology has transformed the way we fish, especially when targeting species like tuna that can be elusive and fast-moving. Sonar and GPS (Global Positioning System) are invaluable tools in an angler's arsenal, enhancing the ability to locate and target tuna more effectively. This guide will walk you through how to use these technologies to maximize your tuna fishing success.

How to Use Sonar and GPS for Effective Tuna Fishing

1. Understanding Sonar Technology

Basics of Sonar

Sonar systems work by emitting sound waves into the water. When these waves hit an object, they bounce back to the sonar unit, which then calculates the distance to the object based on the time it took for the echo to return.

Choosing a Sonar for Tuna Fishing

  • Frequency: Higher frequencies (like 200 kHz) provide finer detail and are good for shallow water, while lower frequencies (50 kHz or less) penetrate deeper water.
  • Power: More powerful sonar can detect fish in deeper water, which is crucial for finding tuna, which often dwell at varying depths.

2. Utilizing GPS in Fishing

How GPS Enhances Fishing

GPS systems help you navigate to and from fishing spots with precision. They can also mark waypoints where fish are found or where specific fishing conditions are ideal, allowing you to return to the same spot precisely.

Features to Look For

  • Chartplotting: Integrated GPS and chartplotting functions can display your boat’s position relative to underwater terrain, buoys, and other markers.
  • Mapping Software: Some systems come with or allow you to add detailed marine maps that can show depth changes, potential fishing hotspots, and other crucial navigational information.

3. Combining Sonar with GPS

Locating Schools of Tuna

Use your sonar to identify schools of baitfish, which tuna often prey upon. Look for large, dense clouds on the sonar screen, often found near drop-offs or underwater structures.

Marking Hotspots

When you find a promising area with active tuna, use your GPS to mark the location. This allows you to return to this spot easily in the future or continue to track the school’s movement.

4. Reading Sonar Displays

Interpreting the Data

  • Arch Shapes: Fish typically appear as arches on a sonar display. The height of the arch reflects the depth of the fish, while the width can indicate fish size.
  • Color Displays: Modern sonars use colors to show the intensity of the returned echo. Generally, stronger returns (like those from larger fish or hard structures) show up in warmer colors like red or orange.

5. Strategic Fishing Using Sonar and GPS

Drifting and Trolling

  • Drifting: Once you mark a hotspot, you can drift through the area, using your sonar to keep an eye on the fish’s depth and adjust your bait or lure accordingly.
  • Trolling: Use GPS to maintain a strategic route that covers various depths and structures known to hold tuna, adjusting your trolling depth based on sonar readings.

Adjusting Techniques Based on Feedback

React to the information your sonar and GPS provide. For instance, if you notice tuna are consistently at a certain depth or area, you can tailor your approach, whether it's changing the depth of your lures or shifting your trolling path.

6. Safety and Navigation

Navigational Safety

Always ensure that your GPS and sonar devices are in good working condition to rely on them for safe navigation, especially in unfamiliar or challenging waters.

Legal and Ethical Considerations

Make sure to use sonar and GPS within legal guidelines and practice ethical fishing, respecting marine life and habitats.


Using sonar and GPS effectively can significantly enhance your tuna fishing success. These tools not only help in locating fish but also in understanding the underwater environment, navigating efficiently, and planning strategic fishing activities. With practice and proper use, sonar and GPS will make your fishing trips more productive and enjoyable.

Read more

The Beginner’s Guide to Tuna Fishing: Tips and Tactics

The Beginner’s Guide to Tuna Fishing: Tips and Tactics

Introduction Tuna fishing can be an exciting and rewarding sport, but for beginners, knowing how to start can be daunting. This guide provides essential tips and tactics for novice tuna anglers, fr...

Read more
Understanding Tuna Behavior: Best Times and Conditions for Fishing

Understanding Tuna Behavior: Best Times and Conditions for Fishing

Introduction Successfully fishing for tuna requires more than just good equipment and technique; it also necessitates a deep understanding of tuna behavior. Knowing when and under what conditions t...

Read more