Snipe, after your post, I think we are on the same page. What you are speaking of are morphological differences between strains. I will further mention that the shape of centrarchid fish change significantly as they grow. They begin as slender little things and as they age they become taller proportionally relative to their length. This is why the power factor exceeds 3 instead of just being 3 for every centrarchid. A power of 3.28 for LMB or 3.44 for BG exacerbate weight for longer lengths. Other fish like TP and carp are very nearly 3 because their shape doesn't tend to change much as they grow in wild populations.
As for whether 180 is too high for Florida strain LMB, this may be so. The problem is that I don't know of any data on the morphological differences between Florida and Northern LMB. It is probably worth deeper investigation. In the samples I referenced, all the CA and TX fish possessed Florida genetics and were intergrades of the two strains. One way to test for the differences would be to see if RW is also bounded 180 for Northern LMB of the greatest RW. If that RW limit is lower using the equation I employ then this would be evidence supporting that intergrade LMB have power factors greater than 3.28 (the number that fits the LMB chart I use). So far, the highest RW that I am aware of for Nortthern LMB is 140.
There are ways to test the various propositions. For example, if the proposition that Florida genes cause LMB to grow faster in length than Northern genes is true, then intergrades starting at the same length and weight would grow differently than Northerns on equal rations. To be true, the Florida interragrade length increment would have to be greater and it's RW would have to be less. If instead the morphology were different then the intergrades would gain RW but the length gained would be less than the Northerns. FWIW, I think either outcome is possible and it completely depends on whether the morphology is different.
I will emphasize that it is evident that intergrades at equal weight and length require more forage to be satiated than Northern LMB. Consumption is ultimately the overlying reason that intergrades grow faster. To grow bigger, there has to be more Consumption. Different morphology doesn't mean that Consumption will increase. On the other hand, greater rates of satiation leads to high RW and high RW can be confused with morphology. This is why I suggest that at equal weights and lengths ... a fixed and equal ration will make evident whether there is morphology difference or whether the difference is related to length increment and underlying effects of that underlying growth impetus has to increase consumption. It is an interesting question on a limited ration ... Will intergrade LMB prefer their shape or have greater length increment than Northern LMB.
Postscript
I wanted bring up just how unreliable standard weight charts are at predicting the weight of any particular fish. First thing. To create a chart, many samples are collected and then this data is regressed to a formula. The chart is the result of that formula.
Problems arise first because of sexual dimorphism. Females are shaped differently because of the production of gametes that are larger percent of their body weight and females consume more and build more body mass to support that effort. But the data includes both females and males and as they get longer the divide between what is normal at a given length for each sex widens. Consider a case where Females are normally 2 times the weight of males at the longer lengths. The equation (and the chart) will dissect the data and this will introduce a standard error as high as 33% just from sexual dimorphism. So imagine a "normal" female at RW 133 according to the chart ... but is really only RW 100. Now imagine a Female that 33% heavier than normal. This female will be RW 177 even though she is really only 33% heavier than average females of that length. For a species where females normally weight 2 times more than a male at a given length ... a female with RW of 100 may indicate very poor condition. .
Last edited by jpsdad; 12/03/23 03:01 PM.
