 Adams River sockeye travel from their spawning grounds to the South Thompson River , then into the Fraser River , and enter the Pacific . From the Strait of Georgia , they spend three years in the open ocean following Arctic currents to Alaska and the <unk> islands . They then <unk> their route to the Adams , completing a round trip of over 4 @,@ 000 kilometres ( 2 @,@ 500 mi ) . They complete the <unk> trip upstream , including navigating the swift waters and rapids of the Fraser Canyon , in just seventeen days . They do not eat during this period ; instead they rely on fat reserves stored up from heavy feeding in the Strait of Georgia in the late summer . It is at this point that the salmon take on their distinctive red hue , with the male fish also developing large <unk> backs and aggressive hooked mouths . How they are able navigate back to their <unk> river is not fully understood , but a highly developed olfactory system is believed to play a part . 
