Supplimental forage base stocking. Done them both. Daphnia magna will survive well until the bgill & or golden shiner populations become established, then D.magna will become extinct.
Will a gravel pit have mud bottom areas? Hexagenia will do well for several yrs on oxygenated muddy bottom areas until "weeds" such as Elodea, Chara, Nitella or other mat formers form expansive beds. OR until the suckers are stocked. The kind of sucker population that you are proposing should keep Hexagenia from becoming very abundant. With bass you better explore crayfish, probably papershell (Orconectes immunis) as supplimental forage.
Evidently you did not believe in the Lakedoctor's SMB - blugill stocking philosophy to produce quality bgills? Did you call any of those pondowners with his SMB-bgill?
Never rely on walleye spawning to recruit walleye into your LMB pond. I hope you can prove me wrong. It will be publishable information. Hatchling walleye IF even successful in a 15 ac pond will never make it to harvestable size before being eaten by aggresive bass. Walleye primarily inhabit benthic zones after they are around 10" (2 yrs in your case). 2"-6" walleye, esp those bottom resting, are as good & easy forage as any minnow. Your spawned fish will never make it to that size before being eaten.
Before stocking any musky, be sure to show your musky the part in the book about eating suckers in preference to spiney walleye or bass.
You will be a lot smarter about raising LMbass with walleye, musky, suckers and bgill in 6 - 10 yrs after your pond is built. After several years of research many State DNR's consider Tiger musky overall (including catchability) pretty much not worth the effort compared to pure strain musky.
Walleye will grow on bgill forage. Numerous "it all depends" here.
Maybe you ought to get your pond builders shove up a wall and create a smaller 1/2 -3 ac pond in one of the sections of the 15 ac. Or with a wall Split the 15 ac pond into two ponds: 12 ac & 3 ac, 13 ac & 2 ac, 14 ac - 1 ac, 10 ac & 5 ac, etc. Use the smaller pond for a second fishery, forage producing pond or REARING pond for the stocker walleye etc. . Have two separate more balanced fisheries instead of trying to create three or four species of balanced sport fisheries in one pond which you will eventually conclude is quite difficult.
