Depth Perception

The right sonar transducer frequency for deepwater fishing depends on the species you plan to target.

- Jim Hendricks

Today, saltwater anglers ply ever-increasing depths to catch fish. California rockfish anglers work structure lying 600 feet below the surface. Alaska fishermen target halibut in 750 feet. Deep-drop enthusiasts seek tilefish at depths of 1,500 feet or more. Daytime swordfish anglers drop baits to 2,500 feet or deeper. Whether fishing the equivalent of two football fields or a half-mile below the ocean surface, each of these fisheries requires highly specialized tackle and sonar transducers with frequencies to penetrate the abyss. Yet there is no one frequency that fits all deepwater fishing scenarios, says Craig Cushman, director of marketing for Airmar Technology Corp., the leading third-party supplier of marine transducers for brands such as Furuno, Garmin, Humminbird, Lowrance, Simrad and Raymarine.

"When an angler asks about transducers for deep water, the first question I ask is, 'Where are you trying to catch fish?'" Cushman explains. While there are dozens of potential frequencies, it often boils down to a decision between a medium or low frequency.

FREQUENCY FUNDAMENTALS