This video shows the actual spawning act of chum salmon and part of the process of excavating the nest and covering the eggs.
Salmon nests are typically called redds.
The female salmon does all the work of preparing the redd for depositing her eggs.
Her goal is to remove enough of the loose gravel so larger rocks with crevices are available to help protect the eggs.
Her eggs will sink into these crevices.
The dominent male remains close to her and attacks any other males that come too close.
He often comes up beside her and quivers his body in hopes of stimulating her to spawn. This video shows him doing this once so watch carefully.
When she is ready to spawn she lowers her body over the redd and opens her mouth.
The male immediately moves beside her and does the same thing. She releases her eggs and he releases his sperm.
Of interest is the subordinate male or males move up at the same time and release their sperm.
They can do this because the dominant male is concentrating on releasing his sperm.
Immediately after laying a portion of her eggs she moves ahead of the redd and begins moving gravel over the redd site.
Her first few digs, however, usually do not move any gravel but drive the eggs into the spaces between the gravel.
You will notice a Dolly Varden (the bright fish with light spots) enters the nest site in hopes of finding an egg to eat. In this case I think the female chum salmon was successfull in covering the eggs.
Salmon usually only deposite a portion of their eggs in one nest. The female will typically move ahead of the nest she spawned in and begin digging another nest. Usually the gravel she covers her nest with is the beginning of excavating another nest.
Female chum salmon typically build four to six redds in succession in one place.
When all of her eggs are buried she stays in the area and defends the nests until death. The male then will go off and look for another female.
Why don't salmon deposite all of their eggs in just one nest?
By having multiple nests it helps increase the chance that some eggs will survive to spring when the fry emerge.