Salmon – Sniffer Dogs and Compass rolled in one

Burren Food Gem #8

Salmon in water Marine HarvestThe second amazing fact about salmon are their navigational skills. They are much better navigators than Christopher Columbus who is said to have been quite bad at finding what he was looking for which was the direct route from Europe to Asia! Vicious rumours say that he only stumbled upon land because the Americas stretched so far north and south that he could not possibly have missed it.

But we digress – back to our favourite fish. Salmon, like eel and some other species of fish, are quite the globetrotters among the inhabitants of the oceans.

After hatching in a freshwater stream, young salmon swim downstream to the open sea, where they enjoy life for 3 to 5 years, covering thousands of miles before deciding its time to settle down and lay eggs in their natal stream.

So how do these fish manage to not only go to the feeding grounds around Greenland without ever having been there, but also find their way back to their home river years later?

According to one theory, it’s mostly due to magnetism. When salmon are young, they imprint on the pattern of the Earth’s magnetic field at the mouth of their native river. Years later, when the salmon head back home to spawn, they home in on that pattern. The scientists behind that theory now say they have evidence that it is exactly how the fish are navigating.

The fish also use their sense of smell to help them locate the exact stream of their birth. Every river has a particular and unique chemical composition which will tell the salmon if they are at the right place. If they go up a river and then realise it is the wrong one, they will turn around and find the right one.

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