They know how many hunters there are, they know how many hares were killed. What they don't know is the overall hare population. You can't have a harvest rate, without knowing hie many hares you start with in the first place! If there are 10,000 hares, and 3,000 get killed, you have a 30% harvest rate. Now, if you don't know how many there are to begin with, but you still kill 3,000, what is your harvest rate? Do you understand now? They know how many were killed, they know how many people are hunting them. They don't know the harvest rate.
The statement is correct, you just misunderstood the wording.
I think I'm an alright guy, I think I'm alright