Pacific salmon migrate with a ‘magnetic map’

There is more evidence that salmon use the Earth’s magnetic field to perform extraordinary feats of navigation. A study suggests that Pacific salmon are born with an in-built "magnetic map" that helps them to migrate over thousands of kilometres. US researchers believe the fish are sensing changes in the intensity and angle of the Earth’s magnetic field.
The epic journey of the Pacific salmon is one of nature’s greatest migrations. The fish hatch inland in rivers and streams, before swimming for hundreds or even thousands of kilometres to reach the open ocean. After several years of foraging at sea, they make their way back to the same freshwater sites where they spawn and then die.
Lead author Dr Nathan Putman, from Oregon State University, said: "The migration is a lot of effort and it is definitely challenging, and looking at it from the outside, it doesn’t seem necessarily intuitive how they could manage that."