how to weigh tope

i have heard there is a way of calculating the weight of tope and other sharks without the use of a scales, you have to measure vaious parts eg. length, girth etc.
does anyone know what this is???
cheers

yeah measure there length and girth alright!!lol,if u can find it.to be honest,im not sure about it,because it depends had they just eaten,etc.and also,like us humans,some may be big boned,others muscle,fat etc.im just offering my moneys worth,it definately wudnt b as accurate as weighing,but then again!what do i know,im just jealous!!!

The measurements (in inches) you will need are the length from nose to fork of the tail and girth.
The weight is then calculated from the following: length multiplied by girth squared divided by 800.
For example a tope measuring 60 inches and a girth of 20 inches will weigh approximately 30lb
60 x 20 x 20 = 24000 divide this by 800 and you get 30.
Hope this helps

cheers mate