Here's why:
* Water Temperature: Salmon prefer colder water temperatures for egg development and hatching.
* Timing for Survival: Laying eggs in the fall allows the eggs to incubate during the winter and hatch in the spring, when food is more abundant and water temperatures are warmer.
* Species Variation: Some salmon species, like Chinook salmon, might spawn earlier in the summer, while others, like Atlantic salmon, might spawn later in the fall.
* Geographic Variation: The specific timing of spawning can also vary based on the location and climate of the river or stream where the salmon are spawning.