http://www.heraldnet.com/article/20151029/SPORTS/151028958/1004/Winter-blackmouth-opening-uncertain-

"Anglers also reported hooking and releasing a lot of chinook “shakers,” as they're called, during earlier coho-directed fisheries in central Sound. This swarm of juvenile fish is composed of both wild and hatchery (fin-clipped) fish. When these sub-legals are hooked and released, there is a certain percentage of mortality, used by WDFW to calculate the “take” of wild chinook, just as if they were adult fish, caught and kept."