FWW, when I worked at a fish company on the Cape many moons ago the goal for a fishcutter was 45% return weight on a bass. 33% for flatfish (sole, dabs, flounder etc.. ). Cod was never bought or sold in the whole, but if it was it would be similar to bass. 45% would a goal but I agree with Basic Patrick that 40% is a realistic number.
Of course when I cut I'm just happy with a filet in one piece without too many bones.
