Salmon are strictly carnivorous creatures that feed on others no matter if they are living in freshwater or saltwater. They are opportunistic feeders and will generally eat whatever they can find. The diet of salmon varies significantly depending on where they are living and the age they have achieved. Generally speaking, salmon spend the first portion of their lives in freshwater where they grow up in streams and rivers. In freshwater, young salmon mostly eat small insects such as mayflies, stoneflies, caddisflies, blackflies, and riffle beetles. Sometimes they eat small amphibians and fish. As adults, they are larger and more capable hunters, and different foods become available to them in the ocean. They feed on other fish, crustaceans, and even mollusks. The foods that salmon commonly eat include shrimp, mayflies, stoneflies, sand eels, grasshoppers, sprats, zooplankton, herring, crayfish, caddisfly larvae, krill, squid, and other fish. Just before adults migrate to estuaries to begin the spawning migration, they stop eating altogether.