Before I retired , I used to work in construction. Many years ago I ran into a bricklayer who lived along the Rock River roughly 100 miles west of Chicago. He loved to catfish, as I do, and naturally enough we swapped a few fish stories during some our more idle moments. He told me he sometimes used a rather unique "fishing technique" that yielded rather spectacular results every time he used it. I don't agree with using this technique as it is not only illegal, but more than a little unsportsman like too imho, and the only reason I mention it here is that it sort of illustrates the point about use of electricity when applied to fish management.

According to this "fisherman's" story, he had cannibalized, and removed the guts from an old antique crank type, wooden encased telephone, the kind you see in old movies? Part of that old telephone mechanism contained a small hand cranked generator which when used as it was designed to be used , delivered an electrical spark which traveled up the phone line to get the attention of a switch board operator. Anyway, he took these parts, added some wiring and attached them to an insulated probe, and this became his sometimes "fishing pole" He told me he would launch his boat into the Rock River, and at the appropriate isolated moment, would drop the probe into the water, give the generator about 5-10 ten hand cranks, and wait. He didn't have to wait long before stunned fish came popping up to the surface. He then just moved about the river picking up stunned fish. Not very nice!

I think fish and wildlife surveys conducted by the Dept of Natural Resources (fish census) in lakes and rivers today are conducted in a similar fashion, albeit legally. Perhaps the electric fish barriers operate along similar lines to either repel fish away from a given area, or stun them if they try to swim though the barrier.