Salmons Salmon population is descending quickly. They have several problems to arrive to places where they spawn and then to return then to the sea also. Salmon cycle is complex and sensitive to changes. As the salmons experimenting changes in their bodies, as an adaptation to live in salt waters, they need to reach the ocean quickly. Nowadays, rivers currents have suffered lot of changes cause the impact of human societies into the environment. One of the main difficulties, salmons have to overcome, is the dams, a big wall constructed by humans, which fragmenting the river flow. Other is the descent of river flow caused by the retention of water into the dams, when the melt ice from the mountains flow down. Scientists have proposed some solutions, but not everybody seems to like it. One of them is to take the fish from the sea and then carry them up to mountains currents. But this method has been proved with a big rate of mortality during the process. Other proposed solution is to open dams doors and rise the water flow of rivers in the salmon migration time. But, of course, electrical companies reject this solution.