SALMON Fall heralds annual return

As the weather chills, local streams and rivers are festooned with shades of the turning leaves. Fall also marks the last weeks in the life cycle of many salmon species who return upstream to spawn.

Millions of migratory salmon return to their home streams to lay eggs. After swimming upstream the female chooses a spot in the shallow, but swift flowing part of the river that is highly oxygenated, called the riffle.

Here she digs a depression in the gravel that will serve as her nest or redd. The eggs are laid in the redd, the male deposits sperm over them, and the female covers the eggs with gravel.

A female may create as many as seven redds before she is finished spawning and each redd may hold as many as 5,000 eggs.

As soon as the salmon enter the fresh water their skins begin to change color, they stop eating and they begin their decaying process. A migrating salmon lives for about two weeks after entering the freshwater.

The carcasses provide a food source to other animals and small invertebrates who in turn provide food for the salmon fry (baby salmon) as they get older.

The nutrients given off by the rotting carcass are important fertilizers to the plants and trees growing on the banks, which provide essential root systems that prevent erosion and protects the streams for further generations of salmon.

There are seven species of salmon in the Pacific Northwest: Pink (Oncorhynchus gorbuscha), Sockeye (Oncorhynchus nerka), Coho (Oncorhynchus kisutch), Chum (Oncorhynchus keta), Chinook (Oncorhynchus tshawytscha), Steelhead (Oncorhynchus mykiss), and Cutthroat (Oncorhynchus clarki clarki).

All of these species have very different life cycles – some spend several years before they migrate up streams; some can run and spawn several times before dying; some only spawn at the mouth of streams, where others need to spawn in lakes.

This unique phenomenon of the salmon running can be viewed in streams and rivers all across Mason County.