They were always around, in the spring and fall they were thick. In 2014 they were so numerous you could cast and bring in 2 or 3 of them hooked on your lure at times. they were maybe 2 to 4 inches long. I stood on the bank of the Ohio river for an hour one day as a continuous stream 4 or 6 feet wide of Shad hugging the bank swimming down river. Hardly any since then. Heavy rains and high water is the thing that may be messing up the spawn in spring. I don't know. It was the 1st of August before the rivers around here finally dropped to normal levels and cleared up this last year.