Very nice SMB - congrats and well done !

In many ponds the first 3 years after initial stocking go well - good growth and numbers. It is when all the offspring start using up space and resources that issues develop. That is when management is most needed in the form of harvest. Many things can cause management problems like weather , overpopulation (imbalance) like small or missing year classes , unwanted water quality issues or plant growth and many more.