I don't think you could really have an excess of sockeye in a river when there are probably plenty of bears around that would converge on the feast. Studies have indicated that when salmon carcasses decompose they release marine derived isotops of carbon and nitrogen that are blended into the terrestrial and fluvial ecosystem as enriching agents in a positive feedback loop. Those nutrients fuel the productivity of the environment which juvenile salmon depend on to live.

As for Dave Vedders comment about sockeye redds being practically on top on each other, it is not an occurance exclusive to the Kasilof. Sockeye, chum, & pinks are termed "mass spawners". They migrate in hordes and will use up every available space in the river for spawning. When there is no more space superimposition occurs in which case an existing redd can be partially or wholly dug up to make room for a new redd. One good example of a stream where mass spawning and superimposition takes place is Kennedy Creek in South Puget Sound, because there are only a few available miles of spawning habitat due to an impassible waterfall not far from the mouth of the creek.