Alewife and other anadromous fish are migratory. They spend more time in fresh water environments than other anadromous Pacific salmonids. Sockeye salmon are one of the many species of fish that are anadromous. Other examples of anadromous fishes are sea trout, three-spined stickleback, sea lamprey and shad. Indigenous fishers mainly work estuaries, lagoons and rivers (for anadromous fish). Unlike salmon, shad retain the ability to digest and assimilate food during the anadromous migration. Those that are anadromous are carnivorous, feeding on fishes or marine mammals. Dams interrupt the migration of anadromous fish. The chum salmon ("Oncorhynchus keta") is a species of anadromous fish in the salmon family. Populations migrating between fresh and salt water (anadromous) have been extirpated. NMFS is responsible for marine species and anadromous fish. Attempts to establish anadromous salmon elsewhere have not succeeded. They are anadromous fish that migrate between fresh and salt water. For example, salmon, an anadromous fish, is not traditionally eaten straight out of the river. These fall into two rough categories, the anadromous and the freshwater forms.