I think first we need a common definition of what broodstocking is. I take it to generally mean the live capture of wild salmon or steelhead and then artificially incubate the eggs and artificially rear the offspring. Then what? Release offspring smolts marked or unmarked? I guess that depends on the purpose of undertaking the broodstocking effort.

Broodstocking can be undertaken to prevent the likely or impending extirpation of a population like was done for HC summer chum salmon. Although habitat degradation limits total productivity, overfishing was the proximate cause of population decline. So the co-managers agreed to terminate the overfishing, and small temporary hatcheries were set up to kick start recovery of populations and to extend them to streams where they had been extirpated. As a recovery effort, this broodstocking program appears to have been successful. As far as I know, summer chum are sustainably returning after the hatchery kick start was terminated, both to the original hatchery streams and some where summer chum had been extirpated.

Broodstocking can be undertaken to add harvestable numbers of fish to a population that is otherwise too unproductive to produce a harvestable surplus on its own. This kind of program is only sustainable when there is a continuous supply of surplus adult fish over and above natural escapement requirements. The broodstock program smolts would have to be marked in order for this kind of program to work, and the fish would have to be able to pass through mark-selective fisheries. Otherwise the mark goes for naught.

The former Snider Creek broodstock program on the Sol Duc may have been such a program. I say "may" because, despite going on for 25 years, no one bothered to set up and systematically collect any data to evaluate the success of the program. Marked fish returned, and so some thought that meant that the program was a success. That is a "feel good" success, since the productivity relative to natural production was never measured, so we'll never know.

Personally I favor broodstock programs that can prevent extirpation of populations when the limiting factor or factors can be successfully addressed. I'm not keen on the idea of using broodstock programs to develop harvestable fish that the wild population is unable to produce. If harvest is what is wanted, then I think it makes better biological and ecological sense to have a segregated hatchery program that is entirely separated from wild stocks. The Chambers Creek hatchery winter steelhead program was one such, except that the CC fish became unable to sustain themselves. (Whether that was avoidable or not is the subject for another discussion.) The key component of segregated programs is having the means to limit the number of hatchery fish spawning naturally in spawning grounds intended for use by wild stock spawners.