Steelspanker,

Pink and chum salmon migrate as young of the year fry at 35-40 mm length or less, especially pinks. Estuary rearing is critical for growth that enhances ocean migration and survival rates. Chinook that migrate as young of year fry or fingerlings are also estuary dependent for growth and increased ocean survival. Yearling chinook smolts may or may not linger in estuaries, as they are larger and not dependent to nearly the degree as smaller smolts. Steelhead smolts are comparatively large, six inches or better, and typically swim right through the estuary and head for the open ocean.

Carcassman,

I kinda' pulled that out of my hat. My empirical basis is the early 20th century commercial fish landings. If historic Skagit pink and chum runs were near that magnitude, commercial landings should have left at least some indication. I think the best estimates put the pink run around 1KK and chums at 200K or so. It's hard to say with chum because seasonal, weather, and market conditions seemed to influence that fishery traditionally along with run abundance.

It's becomming increasingly clear that factors besides the usual freshwater spawning habitat and estuary rearing habitat and ocean conditions influence population abundance. There's still much for the next generation of biologists to figure out.

Ickstream Steel,

As Smalma indicated, oral tradition was not able to affirm anadromy much beyond Gorge Dam on the Skagit. The best information is that spawning chinook (and presumably steelhead) reached Stetattle Creek, Cedar Bar, and Reflector Bar, located in the Gorge and Diablo pools, respectively. Those were the most upstream penetration of anadromous fish in recorded history (oral tradition). The rainbow trout and bull trout of the upper Skagit most likely got there via historic migration past the Ruby Canyon cataracts, probably by temporary features that facilitated migration, or less likely via a cross pass connection between upper Lightning Creek and the upper Similkameen basin, which raises different issues about historic geomorphic fish migration possibilities.

Sg