Ideally, human exploitation ( and by extension, artificial propagation) of salmon should theoretically occur in proportion to sex and age composition of the population at a rate that does NOT threaten their viability.

We fail on all counts with all of our north-migrating chinook stocks.

By virtue of fishing the ocean pasture, fish genetically destined to become old and large are disproportionately exploited due to their vast spatial and temporal exposure to the fleets. There is no sanctuary water for these fish... they are pursued year round for their ENTIRE ocean life... at rates that are unsustainable.

Critics would argue that seasons and closures are in place for most areas... BUT... the migratory critter eventually swims into yet another area and jurisdiction which allows their exploitation, particularly so on their long journey back to spawn.

For those few fish lucky enough to evade capture in the marine killing fields to grow old and large, yet more hooks and nets await as they enter their home basins. Any fish that by the longest of odds managed to survive the hostile ocean milieu faces one last challenge.... virtually no one would consider releasing a large trophy fish caught with hook/line. If that fish is unfortunate enough to bite, it's literally dead meat.

The aggregate impact of these misguided harvest practices weigh heavily against the old/large phenotype. In the age old game of "survival of the fittest" the old/large life history has become a poor fit with the very unnatural selection pressures wrought by the hand of man. We are systematically selecting for smaller/younger fish... and that's what ends up returning on the spawning beds and the hatchery racks.

And while modern hatchery practices advocate for "diversity" in broodstock, spawning them "proportionally" across all ages/sizes only further cements the horribly skewed age-class composition of present day chinook populations.

Genetically speaking, we are harvesting AND propagating our way to ever smaller fish. The "big fish" genes are simply weeded out.

....

As to the wisdom of spawning ONLY the largest fish, I'm not sure that's entirely appropriate in a hatchery environment. First off, that strategy significantly limits the potential broodstock pool.... and may not be sufficient to meet the desired level of production. Secondly, it most certainly further reduces genetic diversity in the population. And thirdly, it may not even be effective in the eventual recruitment of the next generation of large adult spawners because the oceanic harvest machine is still out there selecting out the large/old phenotype.

The only plausible way out of this cycle is to reign in ocean harvest.

Good luck with that.