Agree with all these replies. This measurement can be taken with a measuring tape, it takes no longer and involves no more handling than in cradling the fish to take a picture, takes even less because the fish doesn't even have to come out of the water. As far as I know, this meathod is recommended when one catches a trophy native and would like to preserve it. Take a quality photo to show the color and take the measurements to represent the size. Someone who does reproductions can make you a beautiful "mount."