Comments: Apparently does not comprise genetically distinct, temporally segregated runs within a single river drainage, such as those that characterize the chinook salmon and steelhead trout; however, each coastal stream probably has a distinctive strain adapted to local conditions (Moyle et al. 1989). NMFS (1995) determined that there are six major stock groupings in the region extending from southern British Columbia to southern California.
Moyle et al. (1989) divided coho populations in California into two groups: "big river coho salmon" and "short-run coho salmon" (see GMIGRCOM).