The pair moves upstream and repeats the process. This time the gravel that is dug for the second redd washes downstream and lands on the first redd thus covering it with just the right amount of gravel. What a neat trick these salmon have for protecting their nests. A pair will do this until they are out of gametes or out of energy. Males may spawn with several females if they are strong but females usually just spawn with one male. All of this may take only a day or two once the adults have reached the spawning grounds.