Not real sure why they just decide to close the fishery in march either instead of completely shutting it down if the numbers warrant it. Especially if the weaker earlier component of the run should be protected. Maybe as a compromise to make some happy or maybe to maximize liscense dollars. Seems to me the Sauk run generally doesn't show up in numbers until April. A couple of seasons ago I spoke with an "older" timer at the burger joint in Darrington about the run timing of the Sauk and he agreed April was the main start. In fact he didn't even begin his season until April and said May was a good month.
I would just assume shutting the whole fishery (Skagit and tribs) down to be on the safe side if numbers are down.