If they had traveled to that lake, there would certainly be others that would have been caught somewhere in the 75 or so miles from the two major lakes. Those lakes don't have a conventional spillway. At the dam, it has a catch basin outfall. Basically, it's a big brick and concrete drain where the lake overflows into it and the water drops to the bottom and flows out a pipe at the bottom of the dam.
Sure, the fish could have climbed from the stream and over the dam, but I still think there would have been fish caught further downstream in other waters. Pictures shown on tv appear that the fish are over a foot long, each.