FISH WEIGHT FORMULA
The following is the formula for the use in estimating weight of fish by measurement. Take measurements as follows: Girth at the thickest point, length from the point of the lower jaw to crotch of the tail.
Multiply the square of the girth in inches by the length in inches and divide by 800
For example: a fish measures 38 inches in girth and 59 inches in length, so 38 x 38 = 1,444 and 59 x 1,444 = 85,196, then 85,196 divided by 800 = 106.39 or 106-1/2
NOTE: For International Game Fish records measurements, the girth and entire length of the fish should be taken