The relationship between bull trout and Dolly Varden has a long and tangled history. In B.C., the bull trout is primarily an interior species; however, it reaches the coast wherever large rivers cut through the Coast Mountains. Again, there are a number of life history types — stream-residents, large bodied fluvial and adfluvial populations, and even a few anadromous (or perhaps, more properly, amphidromous) populations. These populations that migrate to estuaries appear to be unique to southern British Columbia but probably at one time also occurred in the Puget Sound region of Washington State. Special care should be taken to protect these migratory populations. Where they come together, bull trout and Dolly Varden commonly hybridize; however, even in the face of persistent hybridization (and back-crossing) they maintain themselves as distinct ecological and genetic entities. At the southern margins of their range bull trout are in serious decline.
Source: Information provided by Don McPhail for E-Fauna BC.
Coastal and mountain streams of Arctic, Pacific, and Missouri River drainages from extreme southern Yukon in Canada to headwaters of Columbia River drainage in northern Nevada, USA, and McCloud River drainage in northern California, USA.
. Page, L.M. and B.M. Burr 1991 A field guide to freshwater fishes of North America north of Mexico. Houghton Mifflin Company, Boston. 432 p