The Atlantic salmon is a world traveller. It is an anadromous fish - one that spawns in fresh water but spends much of its life at sea.
The Atlantic salmon has a scientific description going back to the 1700s, but, even now, much remains unknown about its life history.
The Atlantic salmon's historic range encompassed the North Atlantic Ocean and its freshwater tributaries from Ungava Bay to Lake Ontario and southward to Connecticut in North America, and from Russia's White Sea to Portugal on the European coast.
Many of these runs are now reduced or extinct, especially in the southern portions of the species' range. However, Atlantic salmon can still be found in the rivers of Ireland, the United Kingdom, Canada, Iceland Norway, Sweden, Finland, Russia, France, Spain, and the United States. Click for map
In some parts of Europe, small populations are returning to areas impacted by massive pollution, including rivers in Germany (Rhine and Elbe), some rivers in Poland and even the Czech Republic, and rivers in the Baltic Republics of Lithuania, Latvia and Estonia.
Atlantic Salmon Life Cycle
An Atlantic salmon undergoes many changes during its life. Pea-sized orange eggs are deposited in riverbeds in autumn. Early the following spring, thousands of tiny Atlantic salmon alevin emerge. These alevin are about two cm. long, and subsist on their attached yolk sacs, hiding from predators in the gravel of streambeds. When their yolk sacs are nearly gone, the young fish wriggle up into the water and are called fry until they are about five to eight cm. long.
Atlantic salmon later acquire vertical markings on their flanks, identifying them as being in the parr stage. Parr have dark backs, with 9 to 11 bars, called parr marks, along their sides - which act as camouflage. Parr remain in the river for two to six years, depending on temperatures and food supply.
At a length of 12 to 24 cm., parr undergo a springtime transformation and become smolt. Parr marks are replaced by silvery coats for better camouflage at sea. Their internal systems adapt for saltwater life and they leave their streams, travelling to ocean feeding grounds. Salmon from both sides of the Atlantic rendezvous in the waters off southwestern Greenland. Others travel to lesser-known oceanic or coastal feeding areas. They grow rapidly on a diet of small crustaceans and fish. They also must elude predators including larger fish and marine mammals.
After one or more years at sea, following a hereditary route and timetable, Atlantic salmon return to their home rivers in an extraordinary journey that may span more than 4,000 km. of open ocean. If they return after one winter at sea, they are called grilse.
Entering the river between April and November, they navigate upstream, leaping obstructions up to 3m. high to spawn in shallow tributaries in late fall.
Landlocked Atlantic salmon
Some Atlantic salmon populations never go to sea, inhabiting lake and river systems in areas bordering the North Atlantic. These fish follow a cycle similar to sea-run salmon, except that they migrate between deep-lake feeding areas and spawning grounds along shorelines or in tributaries. They average 20 - 60 cm. in length as adults, and less than 4 kg. in weight.
Population of Atlantic salmon
The Atlantic salmon's sensitivity to environmental change and is dependence upon both fresh and saltwater habitats have made it sensitive to environmental pressures and high-seas overfishing. Numbers have dropped greatly in the past half century. Between 1994 and 1999 the number of large salmon available to return to North American rivers is estimated to have dropped from approx. 200,000 to 80,000. However, over the past few years, the numbers increased considerably to approximately 126,000, giving optimism for this species' future.
On both sides of the Atlantic Ocean the Atlantic salmon has generated a rich cultural heritage over the centuries, based on recreational fishing and on the mystique of the fish itself. Flashing silver as it jumps a 3 metre waterfall, the Atlantic salmon has become a symbol of wildness that is to be cherished into the future. It symbolizes healthy river systems and the international importance of this species.