I'm just reading through the fine print now. They did cover the boats voltage in the methodology. AND did paired trolls not charging 1 line and using that as a control. Switching up which was the control and changing voltages for different effects. Also in the methodology.
I agree that the stats are clunky and difficult to make sense of. I believe it would have been more informative and more intuitive if they had instead used some form of multivariate analyses.
3 results jumped out at me, however:
1/ The early age classes were largely unaffected by electrical differential. That makes sense for me as in the past few years they have investigated the effects of magnetism on salmon and they seem to develop that sense for magnetism along with the ability to see polarized light as they age and return home. Magnetism & electricity are related.
2/ Positive voltages attract & negative ones repulse.
3/ It's a mixed bag wrt exact voltages and ages/species attraction/repulsion
I have had lots of anglers consider voltage to be the same as magnetism. You can use a magnet to make electricity, and you can use electricity to make a magnet, but without the rotational motion within the components of armatures, magnets, and commutators, they are really different animals.
Another angle that is not factored in is, what state of mind are the fish in with respect to voltages? I have had situations where some species of salmon are actually repelled by voltages. One instance was when we were plagued by seals, to the point that there was no playing of the fish. You had to horse them in like a bass angler, other wise they were stolen. We have just been talking about the reception of salmon, and trout, but, we also have to consider the other marine creatures as well. I can only assume that the seals and killer whales etc, are also giving off some sort of a voltage field. So, in that situation, the salmon must perceive the lure voltage as a threat. One chap fishing out of Sooke was plagued by pink salmon. So many that he could not hook a spring. He had one of my Portable Black Boxes, but hadn't used it yet. He hooked it up about mid day, and had 3 springs on in short order, the largest and last one broke him off, and he lost the rig. He phoned me and ordered 4 more. He claims that they not only attract the springs, but the pink catch on that side of the boat dropped by half of what the other side of the boat was catching. So, there you have pinks not liking the voltage, which he was happy about.
One more mention, is that I have found that some trout will respond differently on different lakes. I fished Carp Lake near Mackenzie where I could not make my tuned lures work on the rainbows (14 - 16"). They were not attracted or repelled, and I caught almost 30 that day. Yet, my buddy in Ontario outfished his 7 friends 3 yrs running on rainbows while using my lures, and not by a small margin. Lots to learn and so little time. Covid19, go away!!! Iwannagofishin LOL