Scientists believe that salmon navigate by using the earth’s magnetic field like a compass. When they find the river they came from, they start using smell to find their way back to their home stream.
How do salmon find their way back home?
Animal Magnetism: How Salmon Find Their Way Back Home : The Salt When salmon are ready to leave the ocean and go back to their birthplace, they use magnetism to find their home river.
Yet another question we ran across in our research was “How do salmon navigate?”.
Salmon use both the intensity and the inclination of Earth’s magnetic field to orient themselves. Unlike their navigation by sense of smell (discussed below), this ability appears to be genetically inherited by a salmon, not learned along its migration.
Young salmon learn the smell of their home stream, possibly even memorizing it at various points along the way, as they migrate toward the ocean. As adults returning to freshwater, when they encounter that familiar smell, it stimulates them to swim upstream. So there may be some “testing of the waters” as salmon migrate home.
How do fish find their way back to the river?
When they find the river they came from they start using smell to find their way back to their home stream. They build their “smell memory-bank” when they start migrating to the ocean as young fish.
Why do salmon return to their natal sites?
The ultimate purpose for salmon to return to their home streams and rivers is to reproduce and ensure the survival of their offspring., and simple enough. But why is returning to the natal site part of the process ? Consider the alternative: swimming upstream to just any old river could have some pitfalls.
The how and why of salmon migration. In recent years, studies have shown that in the open ocean environment, salmon use the magnetic field of the Earth to guide their migration. This helps them move from the coastal areas near their spawning grounds to rich feeding areas, and then back again toward the end of their lives.