Does a predator eat from hunger or also opportunity? I dunno.
Dave, I am not so sure its "or". I would say a predator eats from hunger and also opportunity. Without opportunity, for example, how else could a predator eat? Even so, I think hunger is a pretty strong motivator. I think I would equate the need for maintenance with hunger. IOWs, we might consider a predator hungry if it hasn't eaten enough today to maintain its body weight. Hunger must strongly motivate anyone (including any creature or any fish) to eat. Just as a survival mechanism if nothing else.
Dave, for BG prey at the optimum length, it takes less than 2 BG per day throughout the growing season (about 3 every two days) for maintenance. But if just 2 are consumed daily the growth is remarkable with an 80% increase in weight. With 3 consumed everyday the growth almost defies reason with a 438% gain. Imagine an 18" standard weight LMB consuming 3 optimum length BG every day for 180 days growing to 17.96 lbs. Yes, you read that right.
540 optimum length BG consumed over 180 days at the rate of 3 per day will grow an 18" standard weight LMB from 3.33 lb to almost 18 lbs.
Now I will try to make the case that hunger is "probably" a stronger motivator to consume (to eat) than is the opportunity for growth (a round belly). 1 optimum length BG isn't enough for an LMB to meet its metabolic demand and it must eat more than one every day (on average) in order to prevent itself from eventually dying. So there is a strong motivation to consume 2 every day if it can. If it can, it will grow remarkably (80%) just being motivated to meet its maintenance every day. So for the 18 standard weight LMB that is a gain of 2.66 lbs growing from 3.33 lbs to 5.99 lbs.
OTOH, how motivated are LMB to consume 3 optimum length BG every day? I think this is great question. To be sure, an LMB can do this if two conditions are met. First, it must have the opportunity ... there must be optimum length BG available in sufficient density to provide the opportunity. Second, it must have the will to consume the third BG after the second BG has satisfied his need for maintenance. IOWs the consumption of the 3 optimum length BG is determined by the LMBs will to consume beyond what is essential to survive. Dave, 3 optimum length BG isn't a whole lot of food. It represents only 2.72% of an LMB's body weight. An 18" LMB can manage this amount of consumption if it has the will to consume that much. Now if we think about it, it is very uncommon to see this level of consumption for LMB that are 12" or longer. I can't reference a case where a 1 lb grew to 4.5 lbs in 180 days. Now that said, it only takes 3 optimum length bluegill per day to register that growth ...
so if it doesn't happen ... either the will is missing or the opportunity is missing (or probably both in most ponds). But lets say we supplied a 1 lb LMB with abundant optimum length BG providing it all the opportunity required to consume 3 daily... the amount of BG consumed daily above 2 per day would be a measure of its propensity to consume above the maintenance motivator.
I don't know for sure ... but for LMB over 12" ... I think most of the growth comes from the consumption of prey that is motivated by the need for maintenance (hunger). Because an LMB cannot consume a partial BG, the consumption of the BG that takes it over the daily maintenance requirement also provides a surplus of energy that can be assimilated into the body of the LMB as gain. It is sufficient to provide remarkable growth that it is only observed when populations are sufficiently limited to support that growth. In other words, I think most of growth of LMB over 12" does not come from being gluttonous ... but from consuming prey that was consumed to meet their daily energy needs.
I would like to mention that it may behoove adult LMB to limit consumption to the number that meets their metabolic demands (which of course will have a small surplus that allows for growth). For the purpose of survival, it is more efficient use of energy. If every LMB were gluttonous, they would allocate to growth prey they could have later put to use for maintenance. So the prey that are consumed in excess of the maintenance need will not be available to support LMB when they may need them later to survive. To complicate matters, gluttonous consumption would more rapidly increase their weight which would of course more rapidly increase the maintenance needed to support them. So to ensure the survival of the greatest number of adult LMB ... they should only consume as much as they need to survive. It would behoove nature to genetically imbue adult LMB with this conservative behavior as a survival strategy.
Dave, I would like to mention that little LMB are gluttonous creatures. So one may ask what gives? But if one thinks along the same line of thinking ... (What strategy ensures the best survival?) .... we swiftly come to a reasonable understanding. The little LMB consume at much greater rates of consumption so that they can grow to a size that takes them off the menu of their parents. IOWs, it behooves their survival to grow fast (just the opposite of adults). When one looks at the whole picture ... it just makes perfect sense.
Regarding BG farming, I agree with you. Producing substantial crops of BG is important to growing LMB. But I think this only 1/2 of the picture. I think population management is no less important. I will try to put this in the context of cattle ranching. Having great productive pasture doesn't guarantee that cattle will grow well on it. One must understand that there is a limit and that the number of cattle on the pasture in combination with the production of grass forage will determine how well the cattle gain. If an excessive amount of cattle are on the pasture and left there too long ... they will instead decline even though the pasture is in and of itself a great producer of grass forage.
