The Secrets Of Salmon Migration
Salmon migration routes extend for thousands of miles. This amazing fish travels more than the average holidaymaker, through oceans and rivers, from birth to death. The three main groups of salmon species, the north Asian, north Pacific and north Atlantic, all migrate.
Salmon are anadromous, which means they can live in fresh water and salt water. This is no mean feat as it involves quite different demands on the body, depending on which environment the salmon are in. In fresh water rivers the salmon has to retain salt in the body while keeping fresh water out. In salt water it has to do the opposite. Salmon spend most of their lives in salt water. They are born in freshwater, move to salt water, and only return to the same area of fresh water to spawn and usually die.
Salmon eggs are laid in rivers, usually the shallower and quieter tributaries. The salmon hatch and the fry and parr live there until they become larger and able to travel down the river to the sea where salmon migration begins. At this stage they are called smolts. The smolts stay together, probably because there is safety in numbers, and swim vast distances across oceans heading north to where the feeding grounds are rich and easy.
In the case of Atlantic salmon, some will head north from British rivers to the seas around the Faroe Islands. Salmon smolts from Scottish rivers will usually make the much longer journey past the southern tip of Greenland and head north through the Davis Straits to feed. The salmon will spend between one and four years feeding at sea before taking the return migration route back to the river where they started life.
Salmon in the Pacific and Asian rivers migrate in a similar way to their Atlantic cousins. The great rivers of the northwest USA and British Coumbia, as well as the rivers of Korea, Japan and those of the islands of Primorye and Sakhalin is where salmon are reared, and where they go back to spawn. The salmon migration routes all head north from those rivers to the Okhotsk Sea, the Bering Sea, and the Gulf of Alaska.
The salmon industry in the northwest Pacific region of Canada's British Columbian coast was perhaps the most vibrant of any. In its heyday there were some 200 canneries dotted along the coast, all relying on the continuation of the salmon migration cycle. People from all over the Pacific rim worked in the canneries, all races and all kinds, in a surprising degree of harmony.
With mechanisation the canneries grew bigger and more efficient. Today there are only two left. One of the old canneries near Prince Rupert at the mouth of the Skeena river has been turned into a museum. It still has the company accommodation huts, the shops and the stores. The canneries were in effect small villages that provided everything the people had a need for.
Salmon migration is still largely a mystery. In studies it has been established that the salmon do return back to spawn at the very place where they were born. The mechanism that makes this possible is not understood, but the salmon still does it. Salmon migration can sometimes mean a mammoth journey in excess of 10,000 miles for the fish concerned.
