I doubt that the carrying capacity or standing stock of NP as the only predator is much different than that of LMB. I base this mainly on they are both predators and the amount of food to sustain each of them and get good or acceptable growth from them is similar for each of them.
I agree completely Bill. Observation proof is abundant in the many lakes where NP stunt and a few get very big , just like LMB when the food is limited. Can you say "hammer handles". I will check some studies for more.
I'm not so sure that stunting is related to FCR or even standing weights for that matter. I think it more plausible it is related to the number of mouths and the quantity of food. We can always imagine, given sufficient water, few enough mouths to sustain fish and grow them. But to your point that better FCR cannot prevent an overpopulation, yes I think this is the case also.
Eric, I appreciate the article you sent. I've been diving into it and it is just full of information that I would like know and like to know more about. Thank you. I'm not sure to what extent you have contemplated its contents, but I can tell you I will be spending some time with it. One pleasant surprise was the table of energy content of various prey. Interesting stuff man, very interesting. To the point of FCR, I am not at all sure their data can be fully relied on to predict prey consumption. I say this because, my general sense is that it takes more forage than that to grow NP at the rates that the subject lakes were reported to.
Just glancing at the charts on specific consumption rates it is clear to me that the annual consumption from the evidence they gathered is going to support the minimum 2.5 to 3 times body weight to sustain growth that was referenced in my original post. These fish are gaining 2 lbs a year and are growing near maximum rates of growth and so I think by the time I actually do tabulate the results ... the reported consumption is probably too low. What this means, if so, is that the NP were supported by consumption that they could not find evidence for. In some scientific circles, even the thought of a non-observable is not allowed. But perhaps this is a case where it should be and it might be justified by things like the rate of digestion or the loss of the weight of prey due to dissolution in the stomachs of NP.
I noticed what appears to be a paradox. Long Lake, which supported the fastest growth, has what appears to be the lowest specific consumption. Nothing extravagant, just adding the two most prevalent prey (the two others trout & pike are insignificant) ... it is clear that fish from this lake were observed to consume less weight in prey. But one thing I notice. The two types of prey (carp and crawfish) are listed as the prey with the greatest energy density. So I am very keen to understand the consumption in units of energy which may make the lowest consumption by weight less a contradiction.
I've got a little application that can digitize the graphs and so I can transform the graphs into tabular data which I think will be an interesting exercise that will allow us to examine their findings with additional context. There is even temperature data!!!! So we can see if we can spot relationships with temperature. Will be a while, but I will try to report some findings from this data on Sunday or Monday.
I will add one last thing that really spoke to me. In the study, NP did not provide much sustenance to themselves. Neither in weight nor in energy density. But it is the energy density of NP that seems to suggest that it can assimilate greater wet mass from consuming the same quantity of energy (thus greater FCR). The energy density of LMB was reported to be 4186 J/wet-weight for LMB but only 3600 J/wet-weight for NP. So if one were to assume that they assimilated the same quantity of energy from a given consumed quantity, the NP should be able to gain 16% more than the LMB on the same quantity of food. If one or the other is more efficient, then this number would of course move.
