Esshup,
The percent error from interpolation of the mid points ranges from 1.4% to 0.20% for lengths between 8.5" to 22.5". The error is not large and I should have added to incorrect and wrong mathematically ... that interpolation is a practical field method with acceptable error.
I see RW as a way to confirm that individual LMB are fulfilling their genetic potential to grow in length. They are going to put excess energy to use growing their frame .... and if they consume more than that ... that will pack on RW.
The consumption required to grow a 21" 100 RW LMB growing to 22" 120 RW is roughly the same as growing a 21" 80 RW LMB to 22" 120 RW. Applying energetics, the difference in consumption is less than 2%. IOWs there may be little advantage to culling one over the other. Removing either fish should free enough forage for the surviving fish to grow at its potential.
For two fish at the same length and 2 different RWs, RW tells about their consumption over the past 12 months. A 120 RW LMB consumed 20% more than its peer at 100%. Why? Just a better competitor (but not by a lot). The average daily difference in consumption is only 0.05% more for the 120 RW LMB than the 100 RW LMB. Every few days, the 120 RW LMB ate a fish that the 100 RW LMB didn't. As long as forage is abundant, RW should be reflect that abundance with high RW. When there is a lot of variation of RW, this is a sign that forage availability is limiting growth.
Culling just on the basis of RW can work against goals. Different fish have different genetic potential for making growth increment. A slow grower by length can attain high RW and yet not have the trophy potential of its peer that put more energy into growing frame. Its important to understand age and length increment potential when culling fish.
I'm with Boondoggle's thoughts that getting a length and weight measurement that can be put in excel for posterity is a good thing. Honestly, I think that is all that is required. I don't believe waiting for poor RW as incentive to cull fish is a good management method. I think its too late and the damage is already done. To effectively manage maximum future growth (later evidenced by high RW) one must be proactive and that could require culling fish of good RW.
