The Chinook salmon is a group-living, pelagic omnivorous fish. Juveniles feed on rotifers, scratchy crustaceans and zooplankton during the first summer months, and as they grow in length and age, they change their diet to crustacean plankton and some small fish. The capelin is also an important food fish, feeding on the warm-water pike and the cold-water lake whitefish and Atlantic salmon (Salmo salar).
Every spring, it stops feeding and travels upriver from offshore to lay its sticky eggs in the lower reaches of rivers where there is waterborne vegetation. Soon after, it returns offshore to fatten. The eggs hatch after 10 to 20 days, and the young, when hatched, go downstream to the sea to grow. At the end of the first summer, the young of the year can reach a length of 3 to 4 centimeters and a weight of 10 to 30 grams, and the young grow into adults after about 2 years.
One peculiar phenomenon is that in their productive years they devour their own young in large numbers, thus acting as a population regulator.
The capelin can survive in very cold areas. According to research, the furfishes use glycerol as an antifreeze agent, and when challenged by the cold, they convert their body's propionic acid and glucose into glycerol to prevent ice crystals from forming inside their cells.