Fish migrations | Pacific Salmon Migration: Completing the Cycle

Pacific salmon undertake many different types of migrations throughout their lives. After salmon hatch from eggs in freshwater, they eventually adopt a seaward form through a process called smoltification, which involves extensive physiological and morphological restructuring in preparation for a life a sea. Ocean migrations then occur and, depending on the species, salmon will spend months to years of feeding on the high seas, until their inevitable homeward spawning migrations begin. At this time, salmon stop feeding and must rely on stored energy to power return migrations. Upon arrival at coastal rivers, they must transition back into life in freshwater and undertake arduous upriver migrations to natal spawning grounds where they reproduce and die. Pacific salmon migrations are remarkable feats, representing a complex interplay between behavior and physiology.