HI Greg. Did you take a conductivity reading? That would help. Also, do you have a brand name and model on the control unit, or is it something that someone constructed?
I'm not an expert on low conductivity, but just by default (geography), I'm an expert on too high of conductivity and effects on electrofishing.
Let me toss a few ideas at you.
First, you didn't say, but it sounds like you shocked during the day. With water that clear, I always try to electrofish at night, no matter what the conductivity. In low or high conductivity, where electrical fields are not ideal, it's a necessity. So, one thing to try is to shock after dark. I suppose that's not ideal for your work hours or the client viewing everything, but tough circumstances call for tough techniques.
Second, in low conductivity, you want as much surface area as possible on your electrodes. How is your boat set up? Is the boat itself the ground? If so, good. Then, what about the positive electrode? Does it have ring electrodes with droppers? If so, make the droppers twice as long, and put on twice as many. Heck, you can even use higher diameter cable for the droppers. (In high conductivity, we do just the opposite -- take off or reduce size; often I just tape them up to the ring with electrical tape and keep some of them out of the water). Now, I'm not saying this is a miracle and will create huge benefits, but more surface area in the water will create a slightly more effective field for you.
That's about all that I can offer. I'm sure you know that some of this electrofishing stuff can get really complex. My couple of thoughts are just the simple, practical solutions. I always harp on my students and biologists around here to always take a conductivity reading before starting. It's a key piece of info.
Dave
