The salmon life cycle begins as an egg buried in loose gravel in a cool stream that has lots of oxygen. When the salmon first hatch, they are called alevins . They wait in the gravel until they finish absorbing the last of their yolk, then hurry to the surface for a quick gulp of air to fill their swim bladders. 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.