See also: Foulhook, Gaff, Spike, Scratch, and Poke.
It happens. It sucks (hence the string of expletives), because nothing shuts a pool down faster than a foulhooked fish, but when you cover pools and holes effectively, you end up scratchin a fish every now and then.
These fish are spring run, spring spawners. Their residence time in the rivers is from 4-7 days to 2-3 months, most right around 3 weeks.