It is critical to have open passages to natal or home streams for adults to spawn.

A grilse is a small salmon that returns to its natal stream after only one year at sea.

A grilse is a salmon, usually a male of about five pounds, that returns to its natal stream after only one year at sea.

After one, two or three years, the survivors return to their natal streams to spawn.

Having left their natal streams, they experience a period of rapid growth during the one to four years they live in the ocean.

After returning to their natal streams, the salmon will cease eating altogether prior to spawning.

Coho, which return to their natal streams four years after birth, on average, came back last year, in a small vanguard of 16 fish.

Those fish that still have natal streams to return to often face degraded water quality.

The adult salmon then return primarily to their natal streams to spawn.

Exactly which smells salmon use to identify their natal stream is uncertain.