Preheat oven to 375 degrees. In a large stainless steel mixing bowl, combine olive oil, parsley, dill and lemon zest; add walleye filets and toss to coat. Cover bowl with plastic wrap and refrigerate for twenty minutes. Using a mandolin or very sharp chef’s knife, shave the fennel bulbs crosswise as thinly as possible. Cut butter into ¼ inch thick slices and set aside. Line a large roasting pan with 2/3’s of the shaved fennel and add the cup of dry riesling. Remove walleye filets from refrigerator, season with salt and pepper and arrange in pan on top of fennel. Sprinkle remaining fennel on filets, cover with a single layer of lemon slices and distribute slices of butter on top. Cover pan tightly with aluminum foil and bake for approximately twenty minutes or until fish flakes easily. Remove fish from oven and serve immediately on top of fennel, drizzled lightly with olive oil and garnished with dill and parsley. Serve with whipped potatoes for parsnip purée. Suggested Wine Pairing: dry riesling or un-oaked chardonnay.