You can get an estimate. The PL suppliers add an extra estimated 10% to cover for error. It is bullshit as survival numbers are a metric used by all farmers in the industry. From ponds to RAS systems.
I wonder why Peter Letizia repeatedly said they would issue a full harvest report then? Certainly he knew about the issues you mentioned that make counting the young ones difficult.
Do you think he was intentionally deceiving people when the pump was in full force?