How to measure Marlin

[Andaman Andy]

Just how many diffent ways are there to measure Marlin?
I will divide this up into "In the water" and "out of the water".
Are there quick "Rules of thumb" or more tried and tested idea's i have heard of measuring around the wrist of the tail and getting a rough weight from that, anyone use this?
As most of us would like to release the fish what is the quickest way to get a rough weight? i am talking Blues & Blacks.

[TunaTeaser1]

Out of the water it's (length x girth squared)/800

Normally this is pretty accurate.

[flndrpndr23]

I have used this on White Marlin. Not sure if it relates to Blue Marlin. Measure the circumference at the very base of the tail. Each inch represents 10 pounds (approx.).
The test for this was a tournament weighed fish of 78-1/2 #'s. The base of the tail measured 7.5".
Doug

[Patudo]

I find the tail to be a fairly awkward place to measure on a larger marlin because it can be some way behind the transom and hard to reach. Even if you walk your marlin as far up the cockpit as you can go it can be hard to reach the tail on a bigger fish, never mind measure the tail stump accurately, bearing in mind the tail is quite often moving about. That measurement is more for making estimates on one you already put in the boat.

The length and girth formula is the best and if accurate measurements are taken it is normally quite accurate. But not all that easy to do on a live fish either.

To be honest I would trust the eye of a really experienced skipper more than anything else, assuming he is saying what he really thinks, as some will pad out the weight and some will deliberately underestimate. But the obsession with weight is a little pointless for fish that are going to be released.

If I'm put on the spot, I try and take a photo of the fish, then estimate the weight from the photo after it has been released, all the while imagining that it had been caught by someone else.

[marlin_mike_]

just a couple of week's ago a boat caught a large bft did the tape job called it 170# on the boat. at the dock the fish went 167# the formula work's. we use it all the time the only thing we do with black's & blue's is look at the "tail stock" if it's long with a good girth but a skinny tail she swim's to fight another day.