Just like crab test fisheries are done. They gather the data from the test fisheries and develop the model. Once established the quota is set and depending on size the seasons reflect the allowable harvest. Our quota is way down this year so the quota is lower and the season reflects it.
There is no way they can check everyone. an avarage is generated by what they do check. And its not exact science. But the forecast "test fishery" has shown that stocks are down. Also, by haveing limited days, it gives them a better chance to keep up with harvest, so we dont over harvest again. The national marine fisheries manages hali, not WDFW. They just enforce.
So ya, like salmon, its not exact, but this way if they dont reach quota, the season gets extended and you get a better chance of BIG females rolling into the straights as the season extends into that period were the BIGGIES are comin in to spawn. If ya ever get a chance to fish Whiskey creek area in 70 feet of water in the latter part of the season, you may find this out!!!

Years ago in a 7 day stretch, our group netted 1100 pounds!