Would be great if the OP could shed more light on the history of the lake and everything the biologist told him. When I hear of skinny LMB, my mind goes immediately to the notion that there is too much competition for the forage that isn't recruiting sufficiently. In my mind, forage recruited for consumption by LMB are forage that BG are not able to consume. One author I have read said this size is 30 mm or about 1.2" in length. Now definitely a 6" LMB will go to town on such sized BG but if you are not recruiting sufficient numbers to this size ... there is no chance there will be sufficient forage to satiate the appetites of all the LMB. If we understood the average proportionate length that LMB consume, we would understand the proportionate weight consumed on average and from that we could calculate its satiation needs for a year in terms individual BG consumed. I consider satiation to be the quantity required to attain its full potential for growth.
The OP is in a warm climate where LMB can gain 2.6 lbs annually. It's warm and a lot of what they eat goes to maintenance so they are going to have to eat alot of BG to reach their potential. I can say for sure that not enough 1.2" BG are being recruited for the number of LMB that are in the lake. If there were enough, there wouldn't be disappointment, plain and simple. So what is enough? All they need to reach their potential. So the average 1.5 lb female LMB in his location will try to consume 22.7 lbs of LMB to fulfill her potential of growth. How many BG is normal for that consumption? If we know the average proportionate size of fish she is eating, we could use that for to estimate the number. A 1.5 lb LMB takes more BG to reach her potential for the year than a heavier one does. So each size class requires a diminishing number of BG. But a 1.5 lb LMB would eat 840 BG per annum to grow 2.6 lbs if the average BG was 1% of its weight (in the OP's climate).
Here's the gig. The average 1.5 lb LMB will not stop trying to consume that weight of BG. This is the weight required to fulfill all its metabolic needs and fuel its full potential for growth. The will to grow is there ... what may or may not be missing is the means. For larger LMB, their growth depends on what filters through smaller size classes. If the BG forage recruits are sufficient in number, there is potential for ad libitum feeding and maximized growth.
My question is two-fold. Since there are not enough BG being recruited for forage, is this because the BG are not recruiting efficiently? Or is it because the LMB are too numerous? Could both be a problem?
