While human science is only just discovering the basis of magnetoperception in fish, the current evidence suggests that fish have been using it for some time. Two species which are now believed to sense the Earth's magnetic field and make use of this information in their lives are Yellow Fin Tuna and Atlantic Salmon. Both of these species make long journeys through the open ocean.
Yellow Fin Tuna have been scientifically observed to respond to the Earth's magnetic field and in 1984 magnetite crystals were found in the Dermethoid Bone Sinus of this species. Then in 1990 magnetite crystals were also found in the lateral line system of Atlantic Salmon (Salmo salar) and in the head of the Rainbow Trout (Oncorhyncus mykiss).
The ability of animals to detect the Earth's magnetic field, and to use information gained in this way is an active field of research at the moment and undoubtedly the future will answer questions such as; Can fish remember magnetic locations and find there way back to them? and Does a magnetic sense play role in occurrence of beaching whales, or are they simply trying to bring to our attention the fact that, or been driven insane by the fact that, we are polluting and destroying the worlds seas and oceans?