Nature Lab

Fisheries Management

Refining Electrofishing

How much and what type of electricity does it take to capture a 3-pound smallmouth bass swimming in a fast-flowing Ozark stream? How much for a 60-pound blue catfish or flathead catfish living in a large reservoir or big river?

MDC staff  Zach Ford, Andy Turner, and Dave Woods are working with the Missouri Cooperative Fish and Wildlife Research Unit at the University of Missouri- Columbia to answer these questions.

Research partners aim to improve the use of electrofishing for flathead catfish, blue catfish, and smallmouth bass, three of the most popular sportfish in Missouri. “Better methods will give us a more accurate idea of these fish populations,” Ford said.

Ford described how electrofishing works. “Electricity in the water acts like a magnet that brings fish to the surface. This lets us dip them into a holding tank, where we can count and evaluate them.”

Scientists are using new technology to refine the electrical settings. This will allow them to sample sportfish populations more efficiently, reducing stress on the fish and increasing sampling accuracy.

Settings for sampling specific kinds of sportfish in various water conditions will play an important role in MDC’s ongoing effort to standardize sampling, obtain accurate population information, and improve angling opportunities.

Before the project began, MDC staff developed equipment guidelines to ensure safe and effective sampling procedures. “We’re putting electricity in the water, so we’re very careful to turn off electricity when anglers, boaters, and swimmers are in the vicinity,” Ford said.

Electrofishing Research Data 2015–2020

• 1,500+ fish will be captured, tested, and released over the course of this study.
• Generally, 2,500–4,500 watts of power are needed to effectively collect sportfish.
• Volts, amps, pulse frequency, and waveform are all aspects of electricity that can be manipulated to help biologists capture fish.
• The conductivity of the water and of fishes’ bodies plays an important role in how electricity is used to capture fish.
• Using the right waveform, researchers can force some fish to swim toward the boat for capture.