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Weight to lenght ratio


greg long

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Does any-one know of a formula for guageing the weight of a trout by measurement that is relatively accurate? or if not any body interested in creating a table that is reasonably accurate? I usually fish catch and release but recently kept a 22inch fish estimated at 2lb I found it weighed 2lb 91/2 ozs. :confused:

IF YOUR DOG THINKS YOU ARE THE BEST

Don't seek a second opinion.

 

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greg long:

Does any-one know of a formula for guageing the weight of a trout by measurement that is relatively accurate?

Try here

 

http://www.fishbase.org/search.cfm

 

Double click on L/W relation.

 

Then select species.

 

TL - leon

 

[ 23 June 2002, 11:52 PM: Message edited by: Leon Roskilly ]

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Member of the Angling Trust

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Length in isolation is only a guide to the weight of a fish as, ideally, girth should be taken into account as well.

 

It also depends on how you measure the length. For instance, some species have a pronounced forked tail. Do you measure to the fork, or to the tip of the tail?

 

Likewise, do you put your tape measure on the ground next to the fish, or along its flank. If the latter, the fatness of the fish will mean an increased reading.

 

Then there's the condition of the fish, and how much spawn it's carrying, and what it's got in its gut.....

 

However, FWIW, the following table is taken out of an old book called "Fishing Facts", which mentions that this scale was first published in 1893.

 

Trout:

 

17" - 2lb 2oz

18" - 2lb 8oz

19" - 2lb 15oz

20" - 3lb 7oz

21" - 4lb 0oz

22" - 4lb 9oz

23" - 5lb 3oz

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Some more of the Sturdy Scales for Trout and Salmon and a guide for Grayling all taken from a 1940's Allcocks catalogue... Averages measurements from tip of nose to fork of tail....

 

Trout

9" - 5oz

10" - 7oz

11" - 9oz

12" - 12oz

13" - 15oz

14" - 1lb 3oz

15" - 1lb 7oz

16" - 1lb 12oz

17" - 2lb 2oz

18" - 2lb 8oz

19" - 2lb 15oz

20" - 3lb 7oz

21" - 4lb 0oz

22" - 4lb 9oz

23" - 5lb 3oz

24" - 5lb 15oz

25" - 6lb 11oz

26" - 7lb 8oz

27" - 8lb 7oz

28" - 9lb 6oz

29" - 10lb 7oz

30" - 11lb 9oz

 

Salmon

30" - 11.574lbs

31" - 12.770lbs

32" - 14.046lbs

33" - 15.404lbs

34" - 16.848lbs

35" - 18.379lbs

36" - 20.000lbs(how convenient!!)

37" - 21.713lbs

38" - 23.522lbs

39" - 25.428lbs

40" - 27.435lbs

41" - 29.544lbs

42" - 31.759lbs

43" - 34.082lbs

44" - 36.516lbs

45" - 39.063lbs

46" - 41.725lbs

47" - 44.506lbs

48" - 47.407lbs

49" - 50.432lbs

50" - 53.584lbs

51" - 56.864lbs

52" - 60.274lbs

53" - 63.819lbs

54" - 67.500lbs

55" - 71.320lbs

 

Grayling

9" - 4½oz

10" - 6¼oz

11" - 9¼oz

12" - 10¾oz

13" - 13½oz

14" - 1lb 1oz

15" - 1lb 5oz

16" - 1lb 9½oz

17" - 1lb 14½oz

18" - 2lb 5oz

19" - 2lb 10½oz

20" - 3lb 1½oz

21" - 3lb 9½oz

22" - 4lb 2oz

23" - 4lb 11½oz

 

Don't you love it!! They say weights are approximate yet they give them to 3 decimel places!!

 

Chris

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Well, I killed three fish today and weighed them to check the tables and found out that in general they are quite close! I have been under estimating my weights, it is so long since I have actually weighed fish. Plus I don't like to boast (much).

 

anglingireland.info

 

P.S. the three fish were 1lb 11oz, 1lb 15 3/4 oz and 2lb 15oz if you are wondering. Amazingly when I had two fish on today the small one escaped . (it's usually the larger that absconds. I lost a 6or 7pounder last year when I collected a "baby" 21/2 pounder on the tail fly.) :D

IF YOUR DOG THINKS YOU ARE THE BEST

Don't seek a second opinion.

 

http://www.anglingireland.info

Fish Paintings

Linocut fishy prints..

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There is a facility in EXCEL for constructing graphs, so a graph of weight against length can easily be set up.

 

You need a different graph for each species you are interested in !!!

 

Once you have entered a good few of your own carefully weighed and measured fish you can dispense with carrying scales and just measure fish.

 

Obviously there will be individual fish that are fatter or thinner than usual - so the graph will show a "spread" rather than a straight line.

 

The formula given by Umber is fine for salmonids and similarly shaped fish, but the coefficients used (800 for trout) need to be different for species of different shapes . There is an excellent article on this very subject in the current Yearbook of the International Game Fish association.

 

[ 07 July 2002, 10:58 PM: Message edited by: Vagabond ]

 

 

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