“Where was I going?”

Like several other animals, steelhead trout use Earth’s magnetic field to find their way. At least, they do if they were hatched in the wild.

Not all trout are wild, though. Some trout are raised in places called hatcheries. People watch over fish eggs and then release the young fish into rivers or oceans. The released fish are not so good at their directions. Unlike wild trout, they don’t know where to go.

God built magnetic navigators into the fish’s instincts. Can machines mix those navigators up?

It looks like it. Certain machines are at work inside a hatchery. Those machines change the magnetic field around the young hatchery fish. That seems to change something inside the fish too.

When hatchery trout are released into a river that leads to the sea, they should all turn and swim in the same direction. They should go find food and grow bigger and bigger. Later, the same fish should come back to their own rivers to lay their eggs. Wild trout do that.

Hatchery trout don’t. They’re so confused that they don’t turn in any certain direction. They just huddle together.

Can they learn to use the Earth’s magnetic field, like wild trout? No one knows yet. Scientists will track two groups of fish. They will see how many from each group find their way home.