A blackmouth is a resident chinook, one who will live out his entire life in Puget Sound, rather than migrating to the ocean, before returning to the river to spawn. Normally they do not achieve the size of ocean-going fish, though I believe a thirty-plus pounder was caught a few years ago. They are analogous to what we used to call feeder silvers (now commonly called resident coho) who migrate no farther than the north Sound and Strait of Juan de Fuca and return to spawn at three to five pounds.