The females will build gravel nests with their tails called redds . Although some steelhead and cutthroat will live to spawn again, most anadromous salmon will die after spawning. Their bodies feed the stream environment. The journey to and from the spawning grounds is dangerous indeed. Not even the egg is safe.
Some predators prefer eggs because they are high energy sources of food.
Careless hikers, unleashed dogs and other disturbances can destroy redds and either crush eggs or loose them to drift downstream. too much erosion can cause silt to smother the redds and suffocate the eggs. Streamside vegetation and responsible forestry can help reduce this hazard. When the fry emerge from the gravel they are very vulnerable to predators. They are small and need to learn very quickly how to hide. Predators are natural but around dams predators gather to await salmon fry that are spilled over the top or rocketed through bypasses.