As troutdude said, it does, indeed, happen unannounced. I once called the ODFW (trying to glean information for the newsletter and Oregonian article) regarding their broodstock planting program. The lady to whom I spoke seemed a bit miffed and told me curtly, "There is no program" and that it happens when it happens. As I recall, I thanked her courteously. At least I hope that I did so.