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Name: Sana
Status: student
Age: 16
Location: N/A
Country: N/A
Date: Monday, June 17, 2002

How do Salmon know how and when to return to the initial habitat, after migrating miles away.


The current theory is that each stream, river, etc. has a "signature scent". This scent is characterized by the rock and mineral composition that the stream, etc. runs through picking up the chemical components of the rocks and minerals. If this idea does test out and there is one study that indicates it may, all the salmon has to do is find itself nearby in the ocean and it can locate the stream by the streams unique chemical composition or "scent".

We are finding that many animals including fish have the ability to find general direction because they have a built in compass molecules in special cells located in the brain. This compass has been identified in migratory birds. I'm not sure if salmon has been verified to has this too, but I suspect they do.

Most salmon live a set number of years, so when they become sexually mature, they return to breed in their home stream and die of exhaustion from the upstream swim to the streams head waters (or close) where they hatched.

If salmon have this compass and they can detect the signature scent of their home stream, this would explain their behavior. I have to point out that this has not been shown conclusively.

Steve Sample

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