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 many years later to spawn and die.
(Below: Pacific salmon enroute to their spawning beds. Image by Flickr user: USFWS Pacific / Creative Commons)
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.
Here's what we mean:
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 complete their spawn. Image by Flickr user: http://www.flickr.com/photos/soggydan/4041052559/ - 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 ensures 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: http://www.flickr.com/photos/earth_and_env/2847067154/ - 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 to spawn and repeat the cycle.
Many are the ways that salmon fall prey:
(Below: A young bald eagle eagerly tugs at a dead salmon. Image by Flickr user: http://www.flickr.com/photos/jitze1942/4925977474/ - Creative Commons)
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.
If you have opportunity, we recommend visiting a Park’s Visitor Center to take advantage of additional interactive educational programs or materials.
Beyond the Dungeness Spit and across the blue expanse of the Strait of Juan de Fuca is the snow-capped Mount Baker and the Cascade Mountain Range northeast of Seattle, WA.