Whether you believe it or not, it has been suggested that too many fish arriving at the spawning grounds may have a negative impact on egg survival. Why some of you ask? Not all fish arrive at the spawning grounds at the same time, often comming in waves or more regularly in a bi-modal pattern. If too many fish are present the redds established by early run spawners can be dug up and replaced by late arrival spawners. This might seem harmless in that it is natural selection in action, however, many of the newly created redds are thought to have been created higher in the gravel bed leaving eggs prone to being flushed loose during heavy rains and inclimate weather in the winter months. This could leave both early and late spawned eggs out of luck. Again, believe what you will as this is only one of the suggestions made. As for the argument that nature will make its own way, well true... but remember some systems are nolonger left to natures devices, being highley enhanced so returning numbers could be well over historic returns. Anyways, makes for good discussion.