Salmon are fish. They mostly live in large seas, namely the Atlantic Ocean or the Pacific Ocean. Salmon can grow up to 150 centimeters long and weigh up to 35 kilograms. They feed on small crabs and smaller fish.
There are nine different species of salmon that together form a family of animals. They all live very similarly: they experience birth in a stream, and later they swim into the sea. There is only one exception, namely the Danube salmon. He always lives in the river.
All other salmon spend the middle part of their lives in the sea. However, they have their offspring in a stream. To do this, they swim from the sea into large, clean rivers. You sometimes overcome big obstacles this way, for example, waterfalls. The female lays her eggs near the source. The male also releases his sperm cells into the water. This is where fertilization takes place. After that, most salmon die from exhaustion.
After hatching, the young live in the stream for one to two years. After that, the young salmon swim into the sea. There they grow for a few years and then swim up through the same river. They find every turn, even in the small streams, and finally, reach the place of their birth. There the reproduction takes place again.
Salmon are very important to nature. Over 200 different animal species feed on salmon. A brown bear in Alaska, for example, must eat thirty salmon a day in the fall to have enough fat in its body to survive the winter. The salmon that have died from exhaustion become fertilizer, thus feeding many small creatures.
In many rivers, however, salmon have become extinct because they have been heavily fished and because dams have been built in the rivers. Around 1960 the last salmon were seen in Germany and in Basel, Switzerland. There are several rivers in Europe where juvenile salmon have been released from other rivers in order for the salmon to become native again. Many fish ladders have been built into the rivers so that they can overcome power plants. In 2008, the first salmon was discovered again in Basel.
However, many salmon in our supermarkets do not come from the wild, they have been farmed. The fertilized eggs are raised in fresh water in jars and special tanks. Then the salmon are relocated to large grids in the sea. There you have to feed them fish, which you also have to catch in the sea beforehand. Farmed salmon often need a lot of medication because the salmon live in a small space.