Old Hickory doesn't "turn over" like some lakes. It's a riverrun lake with plenty of current. From the picture, it looks like a threadfin kill. Threadfins are about as fragile as anything that swims. The water temperature is what got them.
Yes its a shad kill! Old hickory doesnt turn ove nc its a power genrated lake with lots of flow. But the warm days we had pulled the shad shallow and the major cold fron killed em. There very fragile and die easy. This happens every year! Actually is a good thing imo! Creates a easy meal for the fish that was been waiting all winter! Increases healthiness!