CM -
I agree that Jacks are an important life history and the diversity of the species. However the situation with Puget Sound hatchery Chinook has tipped things out of kilter. The smallest minimum size limit in most marine fisheries for Chinook is 22 inches. Virtually all the Jacks returning to PS hatcheries are now less than 22 inches. With very limit fishing impacts on those Jacks and the high exploitation rates on most hatchery stocks those Jacks are over-represented in the escapement.

To the question on how to select for larger fish. The first step would be to limit the number of Jacks used in the brood stock. With the significant surplus fall Chinook returning to most Puget Sound hatcheries it should be straight forward to select for larger 3 and 4 year old fish (and any 5 years one might encounter).

Last year the Samish hatchery escapement was 2.17 times higher than brood stock needs, the George Adams hatchery had an escapement that was 17.1 times higher than brood stock needs, the Hoodsport hatchery had an escapement that was 3.2 times higher than brood stock needs, The Issaquah hatchery had an escapement that was 2.27 times higher than brood stock needs, Soos Creek had an escapement that was 6.34 times the brood stock needs, Voights Creek had an escapement that was 5.7 times brood stock needs, and Tumwater hatchery had an escapement that was 9.73 times than brood stock needs.

Clearly there are fish to be worked with. It should be a simple matter to look at recent data (code wire tags??) to determine the size frequency of say 3 year Chinook might look like. That based on historical data (catch information from say pre-1960) what portion of the run should be 3 year adults. Use that size to cull all adults less than that size (keeping a few jacks). Take the remaining fish; age them and select for the appropriate number of 3 and 4 year old fish while culling the smaller 4 year olds. Based on the code wire data I have looked at on those hatcheries with 5 times the escapement over brood stock one could potentially make egg take needs with 3 year old greater than 28 inches and 4 year fish greater than 31 inches. The other hatcheries might require of second generation of selection to reach those target after which it should be just a matter of paying attention to the brood selection to maintain the desired size/age distribution.

Doable? you bet!
Take more work? Sure but well worth the effort!

The end result would be increase biomass of Chinook for the orcas, increased value of each fish in commercial fisheries; they are paid by the pound, and higher quality of fish in the recreational fishery all without increased rearing cost and not increase adverse hatchery impacts on the wild fish.

Curt