I was able to work with the data today and might do more but think this is about as far as I can take it. To summarize, I am not convinced the daily rates of consumption are accurate because the metrics are obtained as a snap shot of the moment the NP were sampled. So a number of things could influence the daily rate of consumption when measured in this way. One could be that "fish that are full" are less frequently caught and sampled. So possibly fish that are "filling up" are moving around and being caught in fyke nets or are caught by the hook and line sampling. Also possibly there is more than one period of filling up per day and the morning grub is digested and no longer present when they are caught with the evening grub. There just doesn't seem to be enough consumption to grow these fish @ >2 pounds a year.
The annual consumption ranged from 2.5 g/g/year to 4.1 g/g/year depending on the lake. But the growth reflected maximums when referenced with respect to the ranges of growth historically reported. Long Lake had super growth which reflects the highest growth ever documented of NP that I am aware of. These fish were >6 lbs in year 3. That is remarkable. So I don't think this data gives us a lot to go on with respect to FCR, however, I do think the observed consumption is probably highly correlated to actual consumption (if one will allow me to let a falling tree to make sound when no one was there to hear it)
Because I do think there is strong correlation consumption, I do think the data allows one to make comparisons between the lakes, the growth observed in each lake, and the quality and abundance of prey in each lake.
This was a great find Eric. I learned some things I didn't know. First I didn't know that Northern Crayfish were more energy dense than bluegill or even trout, for example. For me that was a real eye opener. Also I didn't know that carp were 1.79 times more energy dense than bluegill. I have known for a while that "rough fish" presence has been observed to be associated with greater standing weights of LMB .... this was as much a surprise to me as it was to the authors. I guess its possible that rough fish make up for the bad effects by reproducing more nutritious YOY.
When the consumption of prey was transformed into energy ... the consumption was very comparable between lakes. Mary had the lowest consumption and the slowest growth (albeit phenomenal growth anyway). This lake was interesting because crays were also present but were not prevalent in the way they were at Long Lake where the consumption of crays accounted for 42% of annual consumption. Mary had a crappie population and I wonder how much they may have competed for crays. Though NP in Mary grew slower than did Long Lake NP, they were observed to consume a greater weight of prey. So the quality of prey must contribute to growth in meaningful ways where Long Lake was like the perfect storm of carp and crays. I also wonder if calories tell the fish when its time to rest and digest. The NP of Long Lake consumed smallest weight of prey but they appeared to be getting their fill of them (growing at maximum rates of growth). Perhaps the greater energy density allowed them to spend more time on the couch and less time hunting another meal? Certainly other things like cover, weeds, etc probably also play a role. I've attached a spreadsheet below and so everyone is encouraged to browse its tabs and comment.
