Potamodromy in SahnonidaeLiving and Moving in the Fast Lane

Potamodromy is examined for river-dwelling populations of 13 coregonine species, 2 thymalline species, and 19 salmonine species to uncover common and contrasting migratory patterns in flowing waters. Members of these subfamilies probably have recolonized rivers and streams repeatedly over the past million years or more in the face of several glaciations, ice recessions, and interglacial periods. To do so they may have evolved migratory behavioral patterns adapted to life in fast-running, cold, highly turbid, changeable, and unpredictable lotic systems. Their migratory behavior coalesces into three cyclic patterns of movement (trophic, refuge, and reproductive) to gain access at appropriate times in their life histories or seasonal periods to three patchily distributed but critical types of habitat (feeding, survival, and spawning). Trophic and refuge movements to respective feeding and survival habitats show considerable site fidelity and, though changing over individual life spans of some species considered, remain similar between successive generations. Reproductive movements to spawning habitats show high levels of site fidelity (homing) from parent to offspring and for repeat-spawning individuals. Specialized features of potamodromy are briefly discussed in relation to long-term occupation of riverine systems. Comments are made on the complexity of salmonid potamodromy in relation to fisheries management practices.