Dozens of bass rising from a lake in northern Alabama may have looked like a zombie fish apocalypse, but the temporarily stunned fish were actually participating in a research experiment.

For a new study, biologists used "electrofishing," where fish are briefly incapacitated with a weak shot of electricity in their water, to garner data on the biologically diverse Tennessee Valley Authority lakes, The Associated Press reported.

People spend around $48 billion a year to fish recreationally, which is one reason why researchers want to know exactly what's going on in the water.

After getting a dose of weak electricity, the fish float to the surface to be scooped out by researchers, who measure and weigh the creatures along with inspecting them for sicknesses and bugs.

"By looking at the overall health and condition of the fish we collect we can tell a lot about what's going on with the fishery," John Justice, a fisheries biologist who works at the lakes, told the AP.

The fish are put back into the water alive after their checkup and rarely have any problems.

"Generally speaking they recover within a few seconds to a couple of minutes," Justice told the AP.

Electrofishing works through a metal pole that hangs off the bow of a boat and holds three metal cables, which lower into the water. The electrical generator is in the rear of the boat, connected to the three cables with an insulated wire.

A 6-amp charge from the generator electrifies water in vertical and horizontal directions for about 8 feet, stunning fish and other creatures that inhabit the lake.

During a research trip last week on Wheeler Lake near Rogersville, the group caught around 200 bass and crappie, all of which made it back safely into the water afterward.

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