Please allow me to explain. I did not mean that the weight of an individual fish is predictable. It is not possible to predict how much it will eat. But lets say I can know EXACTLY what each fish is going to eat each day because I give each fish a weighed ration in isolation of competitors. Each fish will gain similarly with small variation if the weights of food they consumed are the same. Now the lengths will be a different story. Some will be shorter while others longer even though they weigh nearly the same. I can predict the gain from a known ration but I cannot predict how long any particular fish is going to be. But for fish allowed to eat fixed and equal rations, the shorter fish will have the highest RW and vice versa. I just cannot predict the length of a fish from a known ration. I can estimate length only by assuming RW.
Take another look at Boon's growth chart that I posted. In actuality, the model (the middle curve) only explains around 89% of the variation of weight. Another way of saying that? The model does not predict the weight of any particular fish. I would go further to say that it is not intended to. All the model is trying to do is model the average weight through time. Some fish will exceed the weight modeled ... while others will not. In Boon's case, most fish fall within 20% of the model. So if the model predicts a weight of 1 lb at a particular time, then one can expect samples ranging from 0.80 lbs to 1.20 lbs if the model accurately predicts the average weight of the population. Boon's data is less variable than others I have seen. In part, I think that may be due to all fish consuming as much as needed to be satiated. IMHO, satiation (a proportion of body weight) is governed by how much the internal genetics is influencing growth. If that influence is to grow faster than peers, then that fish will require more consumption to be satiated.
I like the way Bill described it and I like to imagine all the female LMB as beautiful girls. Some are pleasingly plump barmaid types while others are thin supermodel types. But at the same weight and same age, I consider them equal fish. After all, for a state record aren't they both equal fish? IOWs the barmaid will not be docked for being shorter and the supermodel will not be docked for having lower RW.
So there is also the question of whether the model can accurately predict the average weight of a population. To do so, the model has to understand how much the fish are eating. This can be highly variable because it depends on forage availability. So of particular interest to me is this question. "What are the maximum rates of consumption when fish have an unlimited availability of forage (can eat all they want to satiation)." If this can be known, then we can also know by comparison with the model whether fish are growing at their full potential. In this case, in their initial year of life. IMHO, Boon's fish are very close to that maximum. I can't say for sure, but it provides a baseline.
To test the model in a different location I tried to use Lake8's lone sample in Tylertown, MS. (I put his link below). The model predicts with his climate a weight of .254 lbs on 9/14/24 (stocked 07/3/24). At consumption 5% over model the weight on the same date is .289 lbs. But Lake8 only provides a length. He estimates 8" but when I do pixel lengths on the photo the fish is 8.8" We have no group of samples to establish an average sample weight so I don't know whether the sample is reflective of the population, an overachiever, or an underachiever. If an overachiever, the model is pretty close but if an underachiever ... it misses the mark by a long way. The only way to make a comparison of model length is to assume an RW. At .289 lbs and 100 RW the fish would estimate at 8.65" which isn't far from the tree (his actual length measurement according to the photograph pixels) but I doubt that his fish is only 100 RW. They are not the same genetics as Boon's. Lake8's LMB are Tiger F1s and this could explain why the model built on Boon's Northern LMB is under estimating growth in Lake8's pond. There are other possible explanations as well. Warmer than normal in Mississippi while cooler than normal near KC, among possible others
