Boy, Cecil, that's a tough question! I guess the simplest answer is that it depends on the type of control unit you use. As one example, I've got a Coffelt vvp-15 control unit (now sold by Smith-Root, actually). At 300 conductivity, I can submerge 50% of my electrosphere (we have a round steel ball electrode, rather than a ring with droppers), and I can get about 450 V and 6 amps. That really shocks fish effectively, but doesn't kill them. If I go to another pond with 2500 conductivity, and submerge half the electrosphere, I'll be lucky to get 125 V and it will be at least 10 or more amps (very small, but intense field; not very effective for shocking fish; gotta get the voltage higher). I always think of voltage as size of the field, and amperage as strength (the physicists cringe when I say that!
). So, I raise the electrosphere to 20% submergence, and I can get 240 V and 8 amps, which is a reasonable field. So, I have adapted to my conductivity. If I was at Greg's client's pond, I would submerge 100% of the electrosphere, probably get 500-600 V, and maybe only 1 amp or so. That's why I would shock after dark -- big field, but doesn't hit the fish very hard. Different types/brands of control units operate at different voltages, etc., so my example is not applicable to other types.
The "bible" on electrofishing is probably Chapter 8 in "Fisheries Techniques, second edition." The author is Jim Reynolds, and the chapter title is simply "Electrofishing." The book is available from the American Fisheries Society (www.fisheries.org), although we are more than halfway done with the third edition, and you might want to wait before buying. It will probably be at least 9 months before the new one is available, and maybe longer.
