Why do salmon swim upstream?

Salmon return to rivers from the ocean and swim upstream to their original hatching place to lay and fertilize their eggs. Swimming upstream is hard work, and only the strongest complete the journey and spawn the next generation of salmon.

Each species of salmon follows its own schedule of return to the birth stream for reproducing. Experts believe that an inborn sense of smell guides each species of salmon to its original hatching grounds. When the fish leave the salt water of the ocean and enter the fresh water of the stream, they stop eating. Spawning is the last thing salmon do before they die.