Salmon Spawn. Informative details about the how and why of spawning salmon. Plus see our video clip of coho salmon leaping in the Sol Duc River, within the Olympic National Park.
Imagine a fish species that begins life in fresh water, migrates to the salty ocean for years, and then overcomes all odds to return to the exact gravelly stream of its birth 7 years later to spawn and die.
The salmon spawn is one of those very nearly inexplicable events, yet this same amazing event occurs every year as though (unbelievably) a Creator might actually be caring for and nurturing Nature.
(Below: Pacific salmon enroute to their spawning beds. Image by Flickr user USFWS Pacific/Creative Commons)
Were you to visit and view the spawning salmon in action, it might look something like the pictures on this page.
Additionally, here is a clip of salmon struggling to leap the Sol Duc Salmon Cascade during the 2012 Coho Salmon run.
While the exact mechanisms that guide the salmon are not clearly understood, it is believed that their guidance systems may be a combination of sensitivity to the earth’s magnetic field and their sense of smell, which is very strong.
Scientists think the earth’s magnetic signals (magnetoception) guide the salmon to the general position of the river where they were born. As they approach, they follow the scents pouring out of their natal stream, finding the entrance to the river and the exact tributary and stream in which they were born.
(Below: These salmon have arrived at their natal spawning grounds in Issaquah Creek, WA, and will soon pair up, dig redds and then die after completing their spawn. Image by Flickr user soggydan - Creative Commons)
Salmon don’t always end up in their exact birth stream 100% of the time, studies show. A few salmon may end up in a nearby stream, thereby helping to ensure sufficient genetic diversity of the species.
It also helps to ensure that creeks with disrupted environments will eventually become repopulated with new runs of salmon.
Salmon are known as a keystone species, because the entire ecosystem around the salmon spawning streams is dependent upon the nourishment that salmon provide. The ocean nutrients, nitrogen, sulfur, carbon and phosphorus, are transferred to the forest and its inhabitants upon the death of the salmon each year.
(Below: A multitude of bright red spawning salmon are engrossed in their spawning activities in the same gravel stream bed where they hatched many years earlier. Image by Flickr user earth_and_env - Creative Commons)
Just 2% of the salmon eggs deposited survive the many years and hazards of life, managing to return to the stream where they were born in order to spawn and repeat the cycle.
Many are the ways that salmon fall prey:
Upon their death at the completion of the salmon spawn, the nutrients from the many dead salmon nourish every species within the environments surrounding the spawning beds. Birds and other animals drag salmon carcasses hundreds of feet into the forest. One study demonstrated that bears may leave up to half of their salmon harvest unconsumed on the forest floor. Their scat fertilizes the brush and trees.
Additionally, the nutrients drift downstream into estuaries for the nourishment of other species of breeding birds. The number of birds nesting in the spring is strongly correlated to the strength of the salmon run during the prior fall.
Should the salmon spawn terminate, the absence of salmon would create an environmental disaster for nearly the entire ecosystem.
Even this rudimentary understanding of spawning salmon contributes to our appreciation of the awe of Nature and of the beauty and uniqueness of the Olympic Peninsula and the Pacific Northwest.
Learn more about the salmon spawn: If you have opportunity, we recommend visiting an Olympic National Park Visitor Center (in Port Angeles or in the Hoh Rainforest) to take advantage of additional interactive educational programs or materials.
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