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Thread: estimating kings?

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    Member tboehm's Avatar
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    Default estimating kings?

    Is there a basic way or foumula for guessing the weight of kings? IE 1" = 1 pound.

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    Member homerdave's Avatar
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    i know that for rainbows it is L x (girth squared) divided by 800.
    not sure how it works on kings, i have tried it a couple times and the results seemed low ... but then i havent caught a decent king in awhile either...
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    Premium Member Wyo2AK's Avatar
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    I've seen where people have used the same equation as Dave posted, but divided by a different number than 800 for kings... something like:
    Weight = length x (girth^2) / 740

    Can't remember for sure. I think fishnphysician has an equation so hopefully he'll see this.
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    Member fishNphysician's Avatar
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    Wyo2AK's got it right...

    L x G x G / 740 = weight in pounds.
    "Let every angler who loves to fish think what it would mean to him to find the fish were gone." Zane Grey
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    I've seen this formula before. How accurate is it? Has anyone actually ever tested it? I've tested the halibut "length to weight" formula you see in the tide book quite a few times and it's about 25% accurate at best.

  6. #6

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    When I start slaying kings in a few weeks, I'll toss some on a scale and do the LxGxG/740 to check for accuracy..

  7. #7

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    Quote Originally Posted by tboehm View Post
    Is there a basic way or foumula for guessing the weight of kings? IE 1" = 1 pound.
    A 28" fish, is usually around 10-12lbs, FWIW, and I have seen them as low as 8lbs.

  8. #8

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    Quote Originally Posted by Muttley Crew Fishing View Post
    I've seen this formula before. How accurate is it? Has anyone actually ever tested it? I've tested the halibut "length to weight" formula you see in the tide book quite a few times and it's about 25% accurate at best.
    For Kenai king's Doc's formula is the most accurate there is. He can jump in and correct me but I don't think you'll be off more than a pound or two either way. I've tested it on enough fish and I'm very comfortable with the estimate.

  9. #9
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    Default King Weight

    Your friends back home will know no better - tell them they're all 30#+ you'll look like a hero!

    270 - I don't know what you're talking about when we catch a 28" king up here it is AT LEAST 22# ;-)
    Mike
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  10. #10

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    Yeah, this topic came up on another forum I'm sure some of you remember a long time ago and I've always meant to give it a good test. I wish I'd thought of it last fall when I started winter king fishing because I've caught a good "sample" number this winter.

    And that begs another question. Is there a difference between the formula for winter kings vs. spawners? I've caught quite a few winter kings with about a pound of sandlances in their stomachs, and caught quite a few with nothing in their stomachs.

    Also, does this apply to silvers, too? Or is there another multiplier used for them?

  11. #11
    Member TYNMON's Avatar
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    Quote Originally Posted by Muttley Crew Fishing View Post
    Yeah, this topic came up on another forum I'm sure some of you remember a long time ago and I've always meant to give it a good test. I wish I'd thought of it last fall when I started winter king fishing because I've caught a good "sample" number this winter.

    And that begs another question. Is there a difference between the formula for winter kings vs. spawners? I've caught quite a few winter kings with about a pound of sandlances in their stomachs, and caught quite a few with nothing in their stomachs.

    Also, does this apply to silvers, too? Or is there another multiplier used for them?
    I think that higher fitness (i.e better quality and fatter fish) you just lower the divison number... 740 however is already very low and it is hard to accurately perfectly measure some fish and the length values do not take into account that males actually grow (due to kype) on their spawning run.

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    Member fishNphysician's Avatar
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    Quote Originally Posted by fishNphysician View Post
    Wyo2AK's got it right...

    L x G x G / 740 = weight in pounds.
    Just a reminder, the accuracy of the formula depends just as much on the precision and consistency of the measurements.

    L = fork length.... tip of the snout to mid-fork on the tail.
    G = around the "chest".... taken immmediately in front of the leading edge of the dorsal.

    The formula is "bang on" for hens. You won't find a more accurate weight formula.

    The formula is excellent for bucks with typical robust 3 x 5 proportions. On long snooty ones (snout adds length without any appreciable mass, i.e. fish with "empty length") or bucks that have noticeably "slabbed up" (skinny side-to-side and "tall" from belly to back, i.e fish with "empty girth") the formula will tend to over predict the true weight.
    "Let every angler who loves to fish think what it would mean to him to find the fish were gone." Zane Grey
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    I did an informal test a few years ago with water weight. I would weigh a fish immediatly after catch then a couple hours later after the fish was in the fish box (with water going in and out). Both weights were done with the same scale, I found that the fish lost abut 10% of their weight. I was shocked that it was that high. I weighed many 50lb fish, right out of the water, then back at camp they weighed 44lbs on the same scale. I was very surprising how much they lost in water weight.

  14. #14

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    Quote Originally Posted by Gooch View Post
    Your friends back home will know no better - tell them they're all 30#+ you'll look like a hero!

    270 - I don't know what you're talking about when we catch a 28" king up here it is AT LEAST 22# ;-)
    That's funny. I keep digital scale on board to bust myths and keep everything realistic. Amazing how people have zero clue when it comes to king weights.

  15. #15
    Member fishNphysician's Avatar
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    If you are unable to get a precise girth, you can still get a pretty good idea of just how much a fish weighs by using fork length alone.

    Again, this is based on typical 3 x 5 proportions on a fit, healthy salmon.

    The formula is L x L x L x 0.36 / 740.

    It is derived from the classic 3 x 5 proportions I spoke of earlier, where G = L (0.6). Just make the appropriate algebraic substitution in the original formula......

    L x G x G /740 = L x L(0.6) x L(0.6) / 740 = L x L x L x 0.36 / 740

    If it looks like your fish has exceptional girth, adjust the answer upward a bit.

    If you feel the fish is a bit anorexic (suffers from either empty length or empty girth), adjust the answer downward accordingly.
    "Let every angler who loves to fish think what it would mean to him to find the fish were gone." Zane Grey
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  16. #16

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    Is this a universal formula for all king salmon ?

    I'd be curious if it worked on kings from the Copper vs. Yukon vs. Nushagak vs. Kasilof and on and on and on.

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    Member fishNphysician's Avatar
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    Formula was personally developed on Kenai fish by back-calculating my divisor based on taping every Kenai king I could get my hands on between 1996 and 2005. Many were taken from my own boat, but the vast majority were measured on the Riverbend rack. The formula is extremely accurate, especially for hens. I still take a few measurements every summer just to validate the formula among spectators. Funny, for the first time ever in the summer of 2005, I was asked by Riverbend management to stop doing this at their cleaning station. They were afraid the true weights predicted by the formula and confirmed on an accurate scale were jeopardizing tips for their guide fleet. A bit embarrassing when another supposed 50#er (as estimated by the guide) had a tough time breaking the 40# mark against a measuring tape and an accurate scale!

    I believe my formula would be reasonably accurate for any strain of kings where body proportions are in the neighborhood of 3 x 5. A smaller divisor would be more accurate for "stumpier" strains of kings. A larger divisor would be more accurate for "snakier" strains of kings.
    "Let every angler who loves to fish think what it would mean to him to find the fish were gone." Zane Grey
    http://www.piscatorialpursuits.com/uploads/UP12710.jpg
    The KeenEye MD

  18. #18

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    I can't wait to try it out on the "feeders" I catch out there. I carry a scale that I've tested and has an accuracy within about an ounce or two. Next time I get one I'll report on that. And, of course, keep trying it, too.

    Once again, does it work on silvers, too?

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