scampbell,
Google "Guidelines for the Culture of Bluegill Sunfish". Everything you want to learn is in there. FWIW, BG do not handle well below 1" in length and in a culture pond that maximizes production of individual BG, they usually stop growing or grow very slowly at 1.5 to 2 in in length which occurs in about 45 to 60 days. IMO you will be better off stocking them between 1.5" and 2 " and allow them to attain 3" sizes in your much larger lake. Just stock them numerically strong enough to have the survival required to meet their recommendation.
If the biologist recommended stocking the BG at >3", why are you recommending that the OP stock BG smaller than that size?
Sure, thank you for the question esshup. Let's say the OP tries to grow them to a minimum of 3". To get most samples > 3" he will have grown them to an average length of 3.5 inches. Now if he crops them at 1.5 to 2 inches in length, 100,000 BG will weigh 332 lbs. But if he grows them to an average 3.5 inches, the 100,000 will weigh 332*(3.5/1.75)^3.43 = 3578 lbs. Personally, I wouldn't try growing such a high standing weight of BG in that pond ... especially considering he has opportunities to grow more crops. If he tries to grow the first crop to 3", he will lose one opportunity ... plus if he has a fish kill ... then he won't make the goal at all. To further complicate things, the BG need to gain ~ 3250 lbs over the next 60 days. Even if he has great feed and they convert at 1.1 to 1, it will require 3500 lbs of feed over a span of 60 days, that is over 58 lbs of high protein feed per day. That is a very high rate of feeding and he would need to be ultra careful with water quality and could easily lose a whole crop.
Meanwhile, for past 60 days they could have been growing in the lake for free. And if BG are in short supply, then the rates of growth could be maximum rates of growth. But it isn't just this. There are other risks to growing past the 45 to 60 days. He will not know how many BG individuals he produced. So maybe 60,000 or maybe 180,000 BG. If the former, he would be feeding way more than they could eat and if the latter, they would not reach the 3" minimum anyway.
You may argue that the BG will all be eaten. This may be true. But I think that's the point. They need more forage to eat. What will happen is that predators that do well eating the smaller BG will get their fill and remaining BG will grow to larger sizes which can feed larger LMB. This is how the food chain works.
The white paper is a good resource and in it is the most cost effective way to culture BG. I recommend that he follow their protocol ... part of which is to harvest between 45 and 60 when they are anticipated to stop growing.
