Obviously budget cuts have forced decisions to be made as to where the $$$ are to be spent. How does the hatchery make decisions on production quotas for the various salmon species? Do they give the most $$$ to the most endangered specie relative to historical records?
Why less coho/chinook for more chum? I have noticed, notwithstanding last year which I saw lots of chum, that there have been far fewer chum in the C/V in recent years compared to the past.
Chum and Pink are relatively cheap to produce because the are released as fry, at which time they immediately migrate out of the river. Chinook, coho and steelhead are more expensive because most of them are released at the smolt stage (they must be a certain size to clip their adipose fin). They require space for rearing, food, and sufficient water and/or power to maintain cool water in their pools. As between chinook and coho, I had heard that the white chinook stock was chosen because they out-migrate sooner, and there isn't sufficient nutrients in the river for a stock that would stick around in the river longer. I would guess one consideration with hatchery coho would be making sure the hatchery fish aren't out-competing the wild stock. In terms of $ per kg of fish that return, I'm guessing that chinook are cheaper to produce than coho.
In the ocean at least, I would guess that chinook (even white) have a higher value to the sport and commercial fisheries than coho. I believe someone on another thread mentioned that the Chilliwack chinook production by DFO was primarily to enhance ocean fisheries, and that may be the case with all DFO hatcheries. In Washington, some hatcheries are federally funded and were intended to help certain stocks overcome the dams on the Columbia system (and are funded from taxes on the power generated by the dams), and some are funded primarily to enhance tribal fishing opportunities (some hatcheries are run by the tribes themselves).