Pacific Salmon Life Cycle
The wild pacific salmon has a unique and interesting life cycle as they move from cold river streams to the ocean and then travel back to the exact same river to spawn. This migration from fresh water to salt water and back again is what makes salmon an anadromous species of fish. While all pacific salmon go through the same stages of the salmon life cycle the amount of time each stage takes is different depending on the salmon species.
Salmon are born from eggs laid in shallow riverbed streams far inland from the sea. The eggs are laid in the fall and incubate during the winter. About a short to time after being laid black spots can be seen in the eggs which are the eyes developing. This means that the salmon eggs can now be called eyed eggs. At this stage in life the eggs are very fragile and of the thousands of eggs laid many do not make it.
Near the end of winter the eggs turn into alevins, small newly hatched fish that still retain the yolk sac. An alevin has big eyes and a body that is attached to this bright sac which provides nourishment during this time as they grow in the gravel. The alevin stay hidden in the gravel during this period until they have spent up the yolk sac and need to start searching for food.
Once the alevin has lost the egg sac and are free swimming they begin life as a fry and become easy prey for other species. During this stage fry feed and grow larger, avoid predators and learn the basics survival skills of life. Depending on the salmon species some will enter a lake, some remain in the river and once the time feels right they will begin their journey to the sea and become smolt.
Eventually fry begin their journey to the sea and at this stage they must transition to a new type of water through smelting. Smolting involves the physical change where the fish can now live in salt water. From the river to the estuary and into the sea the salmon must adapt to a changing environment.
Adult Ocean Salmon
A salmon starts off in the ocean as a youngster and leaves as a mature adult. There are many factors which will influence how long a salmon will stay in the ocean before spawning such as species and food availability. At this stage salmon make their way all over the pacific coast and can have a wide migration pattern. At this point some of the salmon will be caught by fishermen and become canned salmon.
Adult Spawning Salmon
After a varying amount of time depending on species salmon begin to head home to the streams from which they were born. No one is exactly sure how a salmon can navigate back from the open ocean to the exact stream they hatched from and it truly is one of nature’s wonders.
Once the salmon reach the fresh water river they stop feeding and live off stored fat. Their journey up river is treacherous as they struggle though rapids, obstacles, hungry bears, fishermen, small waterfalls and debris to reach their final spawning grounds and the spot they were born. Only the lucky salmon will make it home and the energy expended turns their skin silvery and sometimes even bright red. A sockeye and Chinook salmon can travel over hundreds of kilometres upriver to reach their spawning grounds while chum, pink and coho salmon will usually spawn closer to the sea.
To spawn the female salmon will use her tail to dig a ‘nest’ in the gravel in a spot that has quick moving water to provide lots of oxygen for the eggs. When the nest is ready the female lays thousands of eggs in the gravel and the male will come and fertilize them with sperm. The newly fertilized eggs float down into the gravel nest and will be covered with gravel. The salmon will remain in the spawning grounds for a few days until they die a few days later. The dead salmon will provide food for many species of other animals as well as nourishment for the river bed and the cycle of life will continue.
If you have a few minutes (5:38), watch this excellent video on the Life Cycle of Salmon which was produced by the Oregon Department of Fish and Wildlife.
If you would like more information about Salmon and the salmon fishing industry, please have a look around this website.
If you would like to support sustainable salmon fisheries please consider one of these brands of sustainable Canned Salmon which can be purchased online on this site. Thank you!