The salmon's life

The salmon's life and reproduction is an amazing natural process !

Salmons are born in a stream. To begin with, they leave their natal stream to join the ocean. Simultaneously, they modify their breathing in order to support cold salt water.
During this period, they guzzle a lot of food to reinforce their muscles.

Nobody know why but then the salmons decide to go back to their natal stream. And by an unknown process, they are able to guide himself through the oceans untill they locate the mouth of their river.

The next step is very impressive because they have to swim up the stream to the source. During this phase, they must cross waterfall, face strong flow and resist to their predators like bears. Very few of them will survive. The survivors will couple and breed.
Finally, they willl spend their last strength to protect their eggs and die when eggs hatch. Sometimes, a salmon keep enough strength to do this travel a second time.