The north sound (river fish) chase the Chinook and pinks into the rivers to feed on eggs, etc. So, they are smaller as they spend less time in the salt.
I think they may be 14" or so at first spawning (females) while the late entry females are more like 16".

The Late Entry fish are creek spawners and enter the streams later. Allows them to grow larger (at a given age) than the early entry fish. Then, factor in the creek residents and those who hang in lakes.