weight per length chart ?

Started by Crow, December 26, 2018, 09:39:18 PM

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Crow

I'd rather "check the chart" on some redfish, or pompano !!
There's nothing wrong with a few "F's" on your record....Food, Fun, Flowers, Fishing, Friends, and Fun....to name just a few !

Cor

#16
Quote from: oc1 on December 27, 2018, 07:04:43 AM
21 pounds, 12 ounces.... or so they say.  But some black drum have deeper bodies than others.

http://txmarspecies.tamug.edu/length-weight.cfm

-steve
I have a conversion schedule and spreadsheat of length to weight for Yellowtail provided by our fish tagging body.     This can only serve as a very rough estimate.    Some Yellowtail are thin and slender other short round and stubby!     The fat ones  have been feeding on anchovy off the coast and you can see it immediately and when you pick them up there is no doubt about the difference in weight despite them being fairly short.
Cornelis

Jeri

Having done some work in fisheries management and conservation, particularly sharks; the conclusion was that length to weight charts are notoriously unreliable for anyone looking for more than a 'guestimate'.

A particular sample set that I worked on for just this objective, was over 900 samples of one species, mixed male and female fish, all caught in one season, all weighed and measured and then tagged and released. The results were charted then the 'best fit' line of representation plotted, along with two further lines at +30%, and -20%, to see whether these 2 further lines would encompass the majority of the results - which they indeed did.

So, at +305/-20%, the length to weight analysis was correct, but that is such a huge margin of error, as to be considered little more than a guess. The variations in fish weight against a given length are huge, and difficult to actually quantify. Fish arriving to an area at the end of a migration, skinny and low weight, fish having fed extensively -high weight. Females in various stages of pregnancy/egg development - variable high weight.

To get a feeling for these potential variations, just look at a weight distribution for human beings, that are all say 6'-0" tall??? Or better still, take a walk down your local mall, and view all the 6' tall people.

Cor

Quote from: Jeri on January 06, 2019, 06:55:48 AM

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To get a feeling for these potential variations, just look at a weight distribution for human beings, that are all say 6'-0" tall??? Or better still, take a walk down your local mall, and view all the 6' tall people.
LOL......  I always note my weight guesstimate of every fish I catch and my estimate is that the ORI length to weight charts are at least 20% of with mine.
Cornelis