Why do kokanee salmon spawn only once?

A

Explanation:

Constructing passage ways near the dams to allow to salmon to swim around blocked rivers. The construction of dams in rivers has blocked the path of  some salmons returning to spawning grounds. The best way to overcome this is to make the passage ways near the dams to allow salmons to swim in areas which have blocked due to dams. So that salmons can returned to the spawning ground and can spawn which leads to increase in their population.

Salmon change color to attract a spawning mate. Pacific salmon use all their energy for returning to their home stream, for making eggs, and digging the nest. ... Unlike Pacific salmon, Atlantic salmon do not die after spawning, so adults can repeat the spawning cycle for several years.