I don't know about cutthroat. And I don't know if the lahotton (sp?) variety differs from west slope and other species. Anyone? I'm pretty sure it is the spring time though.
And I do know that brook trout and brown trout are fall spawners and that rainbow are spring spawners. But each region and specific trout strain could vary - esecially if the hatchery has a hand in their genetics...
here are some quotes I came across online:
"tributaries are the last to open as they contain rainbow trout spawning areas and rules relating to trout fishing have always controlled anglers access to waters where trout are spawning. "
"Rainbow trout spawn in the spring immediately after the ice melts. The usual spawning site chosen is a bed of fine gravel in a riffle above a pool. The female digs a redd (nest) in the gravel by turning on her side and beating her tail up and down. During spawning, the eggs fall into spaces between the gravel and immediately the female begins digging at the upstream edge of the nest covering the eggs with the displaced gravel. The eggs usually hatch in approximately 4 - 7 weeks; however, the time of hatching varies greatly with region and habitat. The fry commence feeding about 15 days after hatching and their diet consists mainly of zooplankton. The growth rate of rainbow trout is variable with area, habitat, life history and quality and quantity of food."
"Brown trout spawn in late fall to early winter, from mid-October to January depending on location. The usual spawning site is in shallow, gravelly headwaters of streams or gravelly shallows of lakes. The female makes a shallow depression (redd) in the gravel into which the eggs are deposisted during spawning. When spawning is completed, the female covers the redd with gravel. The time of hatching and growth rate varies greatly with region and habitat. Brown trout habitat and spawning requirements are similar to the native brook trout, with which it is usually in competition."