Weight formula for GT's...

[Peter Morris]

Whats the weight formula Nomad etc uses for estimating weight of GT's...?

I know its a measurement in length and then girth but I have forgotten whats next in the formula..?

Thanks,
Pete

[Mark Harris]

Pete I believe it is:

lengthxgirthxgirthx2.74/100000 (fish to 30kg up)
lengthxgirthxgirthx2.70/100000 (fish 40kg up)
lengthxgirthxgirthx2.60/100000 (fish 50kg up)

I once copied that from somewhere and I think it was from a post in this forum.

[Colin P]

Pete I believe it is:

lengthxgirthxgirthx2.74/100000 (fish to 30kg up)
lengthxgirthxgirthx2.70/100000 (fish 40kg up)
lengthxgirthxgirthx2.60/100000 (fish 50kg up)

I once copied that from somewhere and I think it was from a post in this forum.

I posted this some time ago.  It is based on research done by charter boats operating out of Latham Island who claim to have recorded length & girth measurements for many GT, weighed on accurate scales, over a number of years.  They suggest that their formulae are accurate to +/- 1.5kg.

Don't think we should repeat the debate about whether GT should be kept out of the water long enough to take a couple of simple measurements - that is a matter of personal preference for each fisherman to decide himself and I guess it boils down to how much you care about the weight of an individual fish v whatever risk to the fish you pose by measuring it.  Personally I would only measure a GT I thought may be the biggest I had ever caught - so all my GT in recent years have gone unmeasured!!

[Geoff Volter]

Is the length measured to the fork or the tip?

[Brock Arifovic]

Fork Voltzy

[Kurt de Villiers]

No, Brock...It's Fu*k Voltyz!

[Mark Harris]

Is the afore-mentioned "Nomad formula" different to this one?

[Peter Morris]

Is the afore-mentioned "Nomad formula" different to this one?

Thanks for the reply Mark...

I think so....Nomads one is different.

Pete

[Ladd Yoshimura]

Here's some info from the Ulua/papio Tagging Program here in Hawaii.

Growth chart:
Length from nose to fork of tail (inches), weight (lbs), and age (years).

7 , .03, 1
14, 2, 2
20, 5.8, 3
25, 11.2, 4
30, 19.3, 5
35, 30.5, 6
39, 42.1, 7
42, 52.4, 8
45, 64.4, 9
48, 78, 10
51, 93.5, 11
53, 104.8, 12
55, 117, 13
57, 130.2, 14
59, 144.2, 15
60, 151, 16
61, 159, 17
62, 167, 18

This Ulua tagging program started in 2000, maybe earlier, by the State of Hawaii and is mainly a volunteer angler-based tagging program.

[Luke Wyrsta]

Here's some info from the Ulua/papio Tagging Program here in Hawaii.

Growth chart:
Length from nose to fork of tail (inches), weight (lbs), and age (years).

7 , .03, 1
14, 2, 2
20, 5.8, 3
25, 11.2, 4
30, 19.3, 5
35, 30.5, 6
39, 42.1, 7
42, 52.4, 8
45, 64.4, 9
48, 78, 10
51, 93.5, 11
53, 104.8, 12
55, 117, 13
57, 130.2, 14
59, 144.2, 15
60, 151, 16
61, 159, 17
62, 167, 18

This Ulua tagging program started in 2000, maybe earlier, by the State of Hawaii and is mainly a volunteer angler-based tagging program.

That's some amazing data!

GTs simply eat so much - they grow so quickly! WOW 

[Jay Burgess]

The above table converted to metric. cm, kg, age (years)

17.78,  0.0136, 1
35.56, 0.907, 2
50.8, 2.63, 3
63.5, 5.08, 4
76.2, 8.754, 5
88.9, 13.834, 6
99.06, 19.096, 7
106.68, 23.768, 8
114.3, 29.21, 9
121.92, 35.38, 10
129.54, 42.41, 11
134.62, 47.536, 12
139.7, 53.07, 13
144.78, 59.057, 14
149.86, 65.408, 15
152.4, 68.492, 16
154.94, 72.121, 17
157.48, 75.749, 18

and graphed...

[Scott Maybury]

I really like the idea of my PB 52 inch GT being 100lb but we estimated it at only 38-40kg.....

Not far off in the grand scheme of things I suppose.....just gotta keep looking for that defiante guaranteed 100% 100lber

Some great info there though re the tagging program, thanks for sharing

[Mark Harris]

I am sure we have all caught GTs of approx the same length but with remarkably different girths.  The variation in "fatness" seems especially marked in this species, and that's why a measurement of length can only ever be a very rough guide to GT weight.

[Peter Morris]

Thats exactly right Mark,

Girth makes an enormous difference....At Elusive in July one was caught at 123cm and its girth was 94cm.
I got one that was 120cm long with a girth on 96cm....

Pete

[Jay Burgess]

Thats exactly right Mark,

Girth makes an enormous difference....At Elusive in July one was caught at 123cm and its girth was 94cm.
I got one that was 120cm long with a girth on 96cm....

Pete

My 119cm from Bugatti last year had a girth of 97cm.