Biogeographic Population Groups (BPG) are divisions within a DPS of contiguous areas with broadly similar physical geography and hydrology. The combinations of these physical characteristics represent differing natural selective regimes for steelhead populations utilizing the individual watersheds. These differing physical characteristics have led to life history and genetic adaptations that can enable the populations to persist in the widely varying and distinctive habitat regimes represented by the BPGs. The purpose of delineating the BPGs is to guide recovery efforts across the Recovery Planning Area to ensure the preservation and recovery of the range of natural diversity of the Recovery Planning Area.
CalFish offers the boundaries of Biogeographic Population Groups from the Southern and South-Central California Coast Steelhead Distinct Population Segments.