That's an unresolved issue that should have been settled by the "harvest" report. The failure to follow through on the harvest report would suggest to a cynical person that the numbers don't "add up".
I recall reading 6000 per pound weekly production was based on stocking 500-600 pl shrimp. The test lot 180 was stocked with 800 pl with a 90+ survival rate. Due to high survival rate, the shrimp tank became crowded and slowed down growth rate.
Stocking 500-600 pl reduces stocking cost per lot and provides faster growth.