Ryan,

Tules are chinook that spawn in the lower river. It is believed that due to their shorter trip they enter the river in a more sexually mature state and thier meat is of less quality when in the river. URB's are an up river spawning fish so they enter the river in a less sexually mature state, thus are better table fare. I don't know what tributary drainages deliniate the boundary of an upriver and lower river fish. However all chinook I've hooked in the Sandy and Clack systems have been nasty skaggy tules.

-Ryan