Life Cycle of Salmon

Salmon goes through four major stages. Spawning, out migration, ocean life, and upstream migration. 

Spawning stage. Female salmon uses her tail to clean and shape the gravel to form strings of nests called redds. While depositing thousands of eggs, their male partner immediately fertilizes them. The female salmon then covers the now fertilized eggs with clean gravel and defends the nests. 

Cold, clean water is vital. While the eggs are growing, nutrients and oxygen are delivered via the flow of stream water and at the same time removing waste. When the tiny fishes hatch, they are attached to their sace for nutrients, at this stage they are called frye sac. When they are ready, they move up through the gravels and emerge into the stream. Once they are one inch long, they are called fingerlin. Fingerlins remember the stream and the smell to return to spawn and die later on in life. 

Out Migration.  Fingerlins' time in freshwater with other salmon could be a few days to a few years. They dwell in backwater and stream margins where the current is weak and have the insects to provide nutrients.  As they grow, they move into main channel. Best pools are deep with large wood and rocks for hiding and shades for insects and varrying water speed. The salmons carried down stream by spring thaw, the salmons go through smolting. Smolting is triggered by increasing daylight and rising water temperature. Color change, kidney change, allowing transition from freshwater to salt water.

Ocean Life. The salmons could live in ocean from two to five years. Tough life. Fishing limit on salmon. While salmon in ocean, travel long distance to get food. Large percent don't survive. Body size increase drastically. 

Upstream migration. Triggered by instinct to spawn. Travel upstream back into the fresh water. Homeward bound fish non longer and survived off body fat. Travel hundreds of miles. Health decline rapidly. Salmon carcasses return nutrients to the river. 

It amazes me how hard salmons work. Thousands of fishes, but few survived and even fewer survived to spawn. It is very sad. 

Why does Salmon being enlished at threatened or endangered species matters? Well, because salmon accounts for a major part of the river's ecosystem. The return of nutrient, the flow of species, and contributing to the biodiversity.