Gut, scale and rinse the fish throughly. Pat dry with paper towels. Heat the oven to 350F. Cut one large pieces of foil that is big enough to wrap each whole fish. In each piece lay the fish. Coat wit olive oil on both sides. On the inside of the fish rub the Jerk seasoning inside. Sprinkle with sea salt and freshly ground black pepper on both sides. Stuff lemon slices in the fish. Sprinkle the garlic on top. Place the butter and thyme on top. Fold and crimp the foil to make a pocket. Lay on a baking sheet and place in center of oven. Bake for 30-40 minutes depending on the size of fish. The skin will feel soft but the meat will be firm.