Every river is different on the coast. The genetic makeup of the fish tends to keep them out in the ocean for different times to fatten up, is the theory. 3, 4, 5, 6+ salt fish are gonna have different weights when they finally come home. Umpqua nooks are my favorite fishery and we've caught adults between 10?-36#. Average size, i don't catch enough to keep tally for the ave.
Check out info on the Sac river in CA, Chetco, Elk, Umpqua rivers in OR, river's inlet in B.C, and the Kenai in AK. Lots of special rivers with big ones. Turns out the big fish are out in the "killing grounds" longer and get caught in commercial nets more than smaller fish, so their kind of in trouble.
Best,