Back in 1979 a UBC student did his masters thesis on board a troller. He focused on the best voltages for chinook and sockeye. Long story short, chinook were best and biggest fish at .5 v and sockeye at 1 v. any time a negative voltage was present, no fish were caught. Unfortunately the results are flawed because he was mixing voltages that were too close together, there was no consideration for the hull voltage signature and some times he was in surface fresh water, being off the Fraser during sockeye openings. Might sound like small change to some, but with what I have learned, it all matters. I know the fish believe me.