Just thought I would share a digital fish scale I recreated for all to use. I've tested it to quite a few fish and it is very close to actual weight. Also are links from this webpage to some weight charts I created that you can take to the river and get an accurate weight while on the river! Enjoy! Fred\'s Digital Fish Scale

Nice job with the charts Fred N.

I am a bit concerned that your divisor (R) is a bit too small for 'salmon/thick steelhead'. Have you ever validated your R value of 650 against real live weights and measurements? I suspect you will find that it over-guesstimates the fish's weight the vast majority of the time.

I have done an analysis on real-life weights against measured length/girth on Kenai River king salmon since 1996, and found a divisor of 740 to be the most accurate overall.

Here is a thread I picked up on another forum regarding LGW formulas, and how well certain divisors hold up in real life. FYI these were done on chunky Skeena strain steelhead typically weighing anywhere from 12-30 pounds. The investigator's formula has a fudge factor that adjusts for sex... pretty interesting findings.

December 12, 2003

KEELIN WEIGHT ESTIMATOR FOR BABINE STEELHEAD

A scientist looks at Babine steelhead weight estimates.

This week I had the good fortune to make the acquaintance of Mr. Tom Keelin. Tom is a dedicated S & S [steel & spey] fisherman, with a scientific bent, who spent two years analyzing Babine steelhead length and girth dimensions versus weight.

Tom created his weight estimator based on physical measurements of 56 steelhead caught and released at Silver Hilton Lodge in 2001-2002 as recorded by Mark MacAneeley, the head guide. A soft mesh net was used to gently lift the steelhead from the water to enable accurate weighing prior to release.

Tom discovered that:
• using the Traditional Formula
length*girth*girth / 800
-gave a weight estimate within 1 lb of actual 7% of the time.
-93% of weights are underestimated by more than 1 lb.

• using the Sturdy Formula
length*girth*girth / 750
-gave a weight estimate within 1 lb of actual 33% of the time.
-67% of weights are underestimated by more than 1 lb.

• using the “Keelin Estimator”
length*girth*girth / 690
-gave weight estimates within 1 lb of actual 81% of the time.
-10% of weights are underestimated by more than 1 lb.
-9% of weights are overestimated by more than 1 lb.
- An interesting part of the Keelin estimator is adding 1/4 inch to the measured length of a hen, and deducting 1/4 inch from the measured length of a buck before entering the Keelin table.

I appreciate your response fishNphysician.

It sounds like you have put a lot more thought and practice into this than I. I based my measurements mainly on king salmon caught on Olympic Coast and on a few steelhead. I agree with you on the 650 value as being mostly an overestimate for steelhead, although it was right on for a 38” long, 18.5” girth that weighed in as a 20-pound hatchery steelhead caught last Monday. Up to that point, I would not mentioned steelhead in 650 value.

Again thanks and I will challenge myself for a larger sampling and accurate database.

Okay, I did some more tweaking on my calculator, adopted the thoughts from fishNphysician, and added another calculation for Halibut. It is not perfect for the Halibut (a little overweight for the shorter lengths and a little underweight for the longer lengths, but a good approximation overall).

So now for those who want it all, included are calculations for Steelhead/Salmon, Halibut, and Sturgeon.

Hopefully it will be useful for some. Take care, Fred.

I just eat them I dont care how they weigh