Salmon are a very important natural resource. They provide many people with jobs and are the main source of food for many animals including bears, eagles, and orca whales. Forests also depend on the bones and flesh of salmon, which are left behind by animals, to provide nutrients to the land and help everything grow.
Salmon Eggs
Photo courtesy of the Corps of Engineers, Portland District |
Salmon start out as eggs in a redd, or nest. These eggs are orange in color and very small. The redd is covered by the mother with small pebbles. The salmon eggs need cool, clean water to flow over them to keep them healthy. This is why the redd is covered with small pebbles. Trees and plants along the sides of streams provide the cool water these salmon eggs need.
Salmon Alevin
Illustration courtesy of Cory Ench |
The eggs are laid in the fall, and they will hatch in the spring. When the eggs hatch, the small fish that emerge are called alevin. These alevin still have a yolk sac attached. This yolk sac will provide the alevin with nutrition until they are big enough to hunt for food themselves.
After about a month, when the yolk sac is completely absorbed, the alevin are called fry. The fry begin to migrate in schools. Some fry stay in fresh water for two or three years while others begin their journey to the sea as soon as they are big enough.
Tree Shaded River
Photo courtesy of ArtToday |
The riparian habitat along the rivers and streams provide the young salmon with a cool, clean place to live. The riparian habitat also prevents soil erosion. Cool, clean water contains plenty of oxygen for the salmon. Logs and tree branches, which fall into the rivers and streams, provide places for the salmon to hide from predators. They also attract bugs, which the salmon need for food.
Salmon Parr
Photo courtesy of the Corps of Engineers, Portland District |
After a short time the fry will begin to develop distinctive parr marks (vertical lines) on their sides. Once their parr marks are developed and they are actively feeding in fresh water, they are called parr. After the young salmon have been in the fresh water for a few months, many begin their journey to the sea. Once they set out on their journey downstream, they will begin the smoltification process. This process refers to the changes that take place in salmon as they prepare to enter the sea.
Hydroelectric Dam
Photo courtesy of ArtToday |
The salmon face many dangers on their journey to the sea. These dangers include hydroelectric dams and predators. The salmon will also encounter polluted waters on their journey.
When the salmon reach the estuaries, a place where salt water and fresh water are mixed, they go through osmoregulation. This is the process of adjusting to salt water. Their gills and kidneys have to adjust to the salt water before they head out to sea.
Silver Colored Salmon
Photo courtesy of the National Park Service |
Salmon will live in the sea for up to eight years. In the sea, they face many predators. A few of these predators are orca whales, sea lions, and seals. They will travel hundreds, and sometimes thousands, of miles in search of food. Once the salmon reach maturity, they head back home to spawn.
Fish Ladder
Photo courtesy of ArtToday |
The salmon go back to the very same estuary that they visited earlier in their lives. Here they go through osmoregulation for a second time. Their gills and kidneys must adjust back to the fresh water so that they can begin their journey upstream. The salmon return to the very same stream to spawn where they were born. On their journey upstream, they encounter even more difficulties than on their journey downstream. Now there are fishermen, fish ladders, waterfalls, and even more predators that they must face in addition to the challenges they faced on their journey downstream.
Bear Carrying Salmon
Photo courtesy of ArtToday |
A few of the predators salmon must avoid on their journey upstream include bears, wildcats, and eagles. The bones and flesh of salmon that these animals leave in the forest provide nutrients to the land. These nutrients help keep everything healthy.
Male Sockeye Salmon
Photo courtesy of the U.S. Fish and Wildlife Service |
On their journey upstream, salmon change colors yet another time. Males change to bright colors, probably to attract females. Females change colors also, but not to such brilliant shades.
Decaying Salmon
Photo courtesy of ArtToday |
Once Salmon reach the place where they were born, they spawn. After their long journey upstream and the spawning act, the salmon are all worn out. A few steelhead and sea-run cutthroat may survive after spawning and return to the ocean after a short time. However, all other Pacific salmon species are called kelts or spawned-out salmon at this stage. They will try to guard their redds, or search for refuge in deep pools, but eventually they will die. Their decaying bodies provide nutrients for stream organisms, which in turn will feed the alevin in the spring.
This is the life cycle of the wild salmon - the story of their amazing life journey from birth in the mountain stream, to life in the ocean, and back to the stream for their final days. This process will continue for many years if the salmon have clean, pure water available. These salmon are a very important natural resource. They are important to people, animals, and forests. We all need to work together to keep our waters pure for the salmon and other fish! Visit the "How You Can Help" page to learn how you can help the wild salmon and the other natural resources of Washington State.
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