Thanksgiving steelhead - and even earlier - are dependent on SAR, smolt to adult return rates. Higher survival rates mean larger run sizes. Larger run sizes mean more fish at the tails - the beginning and end of the runs. Having that wide tail before the peak of the run is what provides fishable numbers early in the season. I've caught early returning Chambers Creek winter runs as early as Thanksgiving and even Veteran's Day, and one October winter run on the Stilly long, long ago.