The pink salmon, or Oncorhynchus gorbuscha, is the smallest of the Pacific salmon, weighing up to five pounds. Known otherwise as the “humpback” or “humpy” because of its very pronounced, laterally flattened hump, the pink salmon is called the “bread and butter” fish in many Alaskan coastal fishing communities. This is because of its importance to commercial fisheries. Sport anglers and subsistence fisherman both benefit substantially from the pink salmon. Pink salmon are native to Pacific and arctic coastal waters, from northern California to the Mackenzie River, Canada, and to the west from the Lena River in Siberia to Korea. On even numbered years, from late July through the summer until mid-August, pink salmon enter the river in numbers so plentiful, it appears one could traverse the river on their backs.
The pink salmon has an average weight of about three and a half to four pounds and average length of twenty to twenty five inches. Adult pink salmon returning to coastal waters are a bright, steely blue on top with silvery sides. The back and tail are covered in black spots. The humpy’s scales are very small and their flesh is pink. As the pink salmon approaches its spawning streams, the male’s bright appearance changes to brown or black above with a white belly; females become olive green with dusky bars or patches above and a light-colored belly. Upon entering the spawning grounds, a male pink has developed its characteristic hump, along with hooked jaws. Young pink salmon are almost entirely silvery, and do not bear the stripes or parr mark common to other salmon.
Between late June and mid-October, adult pink salmon enter Alaska spawning streams. It is quite common to see different species of salmon spawning in the same stream or run as pink salmon. Pink salmon frequently spawn within a few miles of the coast and within the intertidal zone. Spawning in the mouths of streams is also common for the pink salmon. Pink salmon favor areas with fast flowing water over coarse, gravelly floors. Depending on its size, a female pink may carry fifteen hundred to two thousand eggs. Like other salmon, the female pink will lay her eggs in a nest in gravelly areas. The eggs are immediately fertilized by one or more males and then covered further by the digging action of the female. The process is repeated several times until all the female’s eggs have been released. Spawning males and females commonly die two weeks after finishing the spawning process. These eggs hatch sometime during midwinter. These young fry, called alveins, take nourishment from the yolk sac as they develop. The fry swim up out of the gravel and migrate downstream into salt water, in late winter or early spring. Most fry emerge and begin migration during the dark hours. Following entry into salt water, the juvenile pink salmon move along the beaches in dense schools near the surface. They feed on plankton, larval fishes, and occasional insects.
While predation is heavy on the very small, newly emerged fry, their growth rate is rapid. The juvenile pink salmon are four to six inches long by the fall, and are moving into the ocean feeding grounds in the Gulf of Alaska and Aleutian Islands areas. Tag and recapture experiments conducted on the high seas have revealed that pink salmon, originating from specific coastal areas, have characteristic distributions at sea which are overlapping, nonrandom, and nearly identical from year to year.