Fish Migration

Many species of sharks, eels and other fish also undertake massive journeys, usually for breeding purposes, yet people think that fish have terrible memories!

Salmon are well known for their migratory habits.  They migrate in order to breed somewhere safer than their main feeding areas.  This is known as reproductive migration.  The adult salmon live in the open seas of the Atlantic Ocean but return to the freshwater streams and rivers where they were born, to lay their eggs.  They use their sense of smell to find their way.  Young salmon wouldn’t have such a good chance of survival in the open sea – there are too many predators and other hazards; it is safer to start life in a river.  Once they are in the stream or river, the adults stop eating and lay their eggs before returning to the sea once again.  The young salmon hatch and spend up to 5 years in the rivers before making their way out to sea.  Here they stay until they are old enough to return up the river.  Pacific salmon have a similar migration pattern but they don’t return to the sea once they have spawned (laid their eggs); they die in vast numbers once their eggs are laid.

Basking sharks are the second largest shark in the world.  They undertake a 16,000 kilometre migration journey into the deep waters of the Western Atlantic from New England, US.  They head out beyond the equator, swimming so deeply (200 to 1000 metres beneath the surface) that they have never been spotted making the journey.  No one really knows why they migrate as there is plenty of food and warm water in their northern home near Florida.  It is thought that they may be seeking out new breeding grounds.