CUT THE FISH IN 1-INCH PIECES. Place all ingredients except casings in a food processor and pulse until coarsely chopped. Or, pass all the ingredients through a meat grinder fitted with medium holes. Stuff the mixture into sausage casings or form 2 long sausages in plastic wrap. Poach the sausages in gently simmering water for 5 minutes, drain and let cool. If you have used plastic wrap to form the sausages, remove it when sausages are cool. Cut sausages into 6-inch lengths. To serve, grill the sausages or place under a preheated broiler. Since the sausages are already cooked, we want only to reheat them and crisp their skins. Makes 8 Sausages, or 4 Servings