With nice BG like in your picture, your time and money might be better spent creating some cover so the spawns this year you will have get a better chance at survival. Some dense cover targeted around and close to spawning beds and around the shallow edges.
A dozen pairs will spawn a gazillion youk sac fry, but if they have no place to hide get wiped out quickly before they get to a larger size.
I'm no expert, just what I would do in my pond if I wanted more BG survival.
Even temporary cedar trees laid out along the shore with ropes on that can easily be removed if a person doesn't want them there all the time.
