Salmon have one of the most amazing homing instincts in the natural world. The fish are born in rivers and streams often far inland where they live for their first two years. Then they swim down-river and out into the sea, which becomes their home for the next two to four years.
After growing plump and strong from the rich feeding in the sea, the salmon turn round and head back to the freshwater spawning ground where they were born. What is incredible is that every fish tries to find its way back to the very stream where it started life as an egg. Only those that are caught by fishermen or die in some other way on the journey fail to make it. The rest find their way upstream to the very tributaries where they were hatched. Here the females lay their eggs. The males fertilize them, and the eggs are buried in the gravel until they hatch and start a life of their own.
Experiments have shown that salmon manage to pinpoint the place they were born and find their way to it thanks to a highly developed sense of smell (or taste). Salmon that have had their nostrils blocked with cotton wool have been lost. If this is true, it explains how they find their home once they are in the river. But not how they navigate in the open sea. Perhaps they get their bearings from the sun and the stars. Maybe changes in water temperature help guide them. We still do not know for certain how they do it. Not that that worries the salmon. They just carry on coming home as their ancestors have been doing for millions of years.
Picture Credit : Google
