When spawning, males develop humped backs, hooked jaws and reddish-yellow sides. The females tend to be more greenish. Pink salmon begin their downstream movement almost immediately upon emergence from the gravel and move rapidly into near-shore nursery areas and shallow marine waters. After about 18 months at sea, pinks return to their natal streams to spawn. In North America, important spawning populations occur from the Puyallup River in Washington northward to Alaska and eastward to Canada's Northwest Territories.
Pink salmon rely heavily on freshwater and nearshore habitats during their life cycle.
They feed on larval insects, copepods, crustacean larvae, and other invertebrates. Spawning primarily in the lower reaches of coastal rivers, pink lay eggs in gravel that is 1.3 - 10.2 cm in diameter. Pink salmon encounter numerous natural and human induced threats to their survival, such as, run-off of herbicides and pesticides, dams, urban development, and industrial waste. All can lead to increased mortality of pink salmon. In addition, shoreline development and the filling of marine wetlands can significantly affect the near-shore environment, negatively impacting pink salmon before they head out to the ocean.