How old is a salmon before they spawn?

Answer 1

It can be a few days to several weeks, depending on many factors...the health and stamina of the fish, the conditions of the river, how fast the water is flowing, and how far up river the fish needs to go to return to the point or near the point where it hatched. The salmon must reach a point far enough up the river where salt water can't reach the eggs. Some salmon, for example the humpback or pink salmon that spawn in the Indian River in Sitka, AK, the trip can take just a few days. For others, for example, the Chinook, or King salmon that travel up the Feather River in Oroville, CA from the San Francisco Bay, it can take weeks.

Answer 2

As far as it needed to reach the spawning grounds. Chinook and sockeye salmon can travel as far as 900 miles inland to reach their spawning grounds.

Answer2: In addition to the above comment, I read a very interesting article about the salmon. In order to breed many salmon species swim upstream, facing turbulent waters along the way. Instead of being overwhelmed by the rough water, these fish actually take advantage of it. The do not plough through chaotic water. Instead when swimming upstream, they conserve energy by using vortices, or miniature whirlpools , that form where the water flow is disturbed by rocks, branches, or other objects. As the vortices form on alternating sides of an object, the fish curve their bodies from side to side and glide between the pockets of turbulence. Some schools of fish use the vortices created by the fish swimming in front of them, effectively riding in their wake. The fish can take advantage of the turbulence created by their own bodies. Researchers hope to borrow from the salmon's efficient swimming style to harvest energy from slow-moving water.