The walleye that swim in the cold, murky depths of Lake Erie are the waters’ apex predator, sleek torpedoes of teeth that dine on shad, minnow and any other fish smaller than themselves. They do not, as far as marine science has determined, dine on lead pellets the size of golf balls or precisely-trimmed fillets of other walleye. So when Jason Fischer, director of the Lake Erie Walleye Trail tournament series, pulled handfuls of lead sinkers and fillets from the bellies of some prize-winning fish, he knew he had a hell of a problem in his hands. There’s nibble-around-the-edges, cut-the-corners...