Sockeye salmon (Oncorhynchus nerka), also called red salmon or blueback salmon, is an anadromous species of salmon found in the Northern Pacific Ocean and rivers discharging into it. This species is a Pacific salmon that is primarily red in hue during spawning. They can grow up to 84 cm in length and weigh 2.3 to 7 kg.  Juveniles remain in freshwater until they are ready to migrate to the ocean, over distances of up to 1,600 km. Their diet consists primarily of zooplankton. Sockeye salmon are semelparous, dying after they spawn. Some populations, referred to as kokanee, do not migrate to the ocean and live their entire lives in fresh water.