Micro -
Some interesting ideas - as others have stated I like that folks are thinking - a couple of comments/clarifications.

Proposal #1 - Actually the information that is becoming available would seem that wild brother and sisters may breed more frequently than you think. Recent DNA work that allows tracking indivual families have found survival of indivual redss varied considerably with just a small handful of pairs of fishing producing lots of fry and others none at all. Thus the majority of the ofspring maybe from just a few parents.

Also need to remember most wild population started with just a small handful of founding adults. A recent real world example would be the even year pinks found in the Snohomish system. As you probably know few even year pinks are found in Washington. In 1980 a total of 150 spawners were seen in the Snohomish that population has grown until as many as 80,000 are expected back this year.

I think it would be just as likley that siblings may breed together in a hatchery as the wild.

Another factor to consider with anadromous fish is that after the fish are released they experience alot of natural selction - depending on the species it is typcially for less than 1% to as many of 20% of the smolts to survive to adult hood. Clearly lots of chances for the village idiot to culled from the breeding population.

Proposal #2 - By their vary nature hatcheries tend to be selctive. Sometimes it is good, sometines not so good. The real point is that managers need to pay attention to these details and make sure that clear plan is laid out with evaluation of whether goals are being met.

An example of steelhead program where the size of the fish were rigorously selected is the Skamania Summer steelhead. Historically the fish were most 1- salt fish. However to develop larger fish the largest returning adults (especially males) were selected. Over several decades the result was that most of the returning adult Skamania fish were 2 and 3 salts. It is interesting that when hatcheries practices were changed to remove size selction (either larger or smaller) from the breeding program the returning adults began getting smaller and younger. 15 to 20# hatchery summer steelhead are not nearly as common as two decades ago.

The key in releasing fry from a hatchery is to do so that they leave the river as quickly as possible. That is plant them as true smolts - that means that depending on the species some may need to be reared for a year or more (steelhead, coho, and some chinook).

Robert -
In mother nature large swarms of smolts leaving the river is the way it should be. With large abundances (sockeye, pinks, chums) 100,000s or millions of fry maybe leaving the systems in a very short time period.

Regarding the genetic interaction between hatchery and wild fish. The information currently available is somewhat of a mixed bag. In many cases despite some real concerns from many of us the remains discrete wild stocks. From a paper you cited:
"Malibu Creek, the southernmost anadromous population, maintained anadromous and resident spawners carrying the dominant southern "wild" haplotype." Not what you are predicting.

Retarding increasing the number of carcasses on the systems. clearly having lots of carcasses returned a lot of nutrients to the systems. Those nutrients were incorporated into the systems by large mammals and other predators/scavagers dragging the carcasses up into the reparian areas or directly recycling the nutrients themselves. The other process was the trapping of the carcasses in the river channels until they rotted releasing the nutrients. The carcases typcially were trapped in log jams, side channels, etc. Unfortanely we as a society have so altered many of our systems that where would the predators/scavagers live or where is the channel complexity to trap the carcasses. It is further compounded by changes in the hydrograph - that is flooding is much more common today causing the carcasses to wsshed to the marine waters - doesn't do much for the freshwater productivity though may have the situation for crabs etc.

In short without habitat improvements adding carcasses is not likley to produce the expected benefits. It will be interesting to see if there are any benefits (large runs) on those systems where the number of carcasses have dramatically increased. For example in recent years (the last 2) the biomass of wild spawning salmon in the Snohomish has been between 3 and 7 million pounds/year - up from 3/4 to 2 million pounds/year for the last several decades. At the current escapement levels adding a few 10,000s carcases will not make much difference.

Tight lines
S malma