what is salmon spawning

what is salmon spawning

1 year ago 116
Nature

Salmon spawning is an annual fish migration event where many salmonid species swim back against the stream to the upper reaches of rivers to spawn on the gravel beds of small creeks. Adult salmon spawn in freshwater, where female salmon lay thousands of eggs that are fertilized by male salmon. Spawning can occur in spring, summer, fall, or winter and depends on the salmon species. After spawning, adult salmon die, and their bodies provide nutrients for the freshwater ecosystem. Eggs are buried in gravel nests, called “redds,” and salmon can stay in their eggs for several weeks to months until they hatch. Once eggs hatch, the juvenile fish, called “fry,” can stay in the gravel nest to feed for 3-4 months. As juvenile salmon grow, they may remain in the freshwater rivers anywhere from a few hours to several years, depending on the species and other environmental factors. As juvenile salmon swim towards the ocean, they begin the process called smoltification–transitioning from living in freshwater to living in saltwater. Species of salmon can spend from 1 up to 6 years in the ocean as they mature and grow into adults. While in the ocean growing, salmon feed on plankton, fish, and squid. Once they reach maturity, adult salmon return to their natal streams to spawn, guided by currents, stars, and the Earth’s magnetic force. The journey upriver is a difficult one, and salmon do not eat during this time, but live on fat stored in their body. After spawning, all species of Pacific salmon and most Atlantic salmon die, and the salmon life cycle starts over again with the new generation of hatchlings.

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