I re-ran that same analysis giving the hatchery the benefit of the doubt that it could achieve a consistent recruit ratio of 3:1.... nearly four times that of natural production. (BTW, even my beloved Kenai River with intact habitat and chinook escapements harvested down to MSY is incapable of that consistent level of production.)

Again the other parameters remained the same... 500 fish baseline population, 100 wild brood fish taken for the hatchery, recruit ratio for wild spawners = 0.8, and recruit ratio for hatchery spawners = 0.68.

The boost the hatchery provides in the first generation is an impressive 24% bumping the return to 620 fish. However, the reduced fitness of hatchery spawners quickly erodes those gains in subsequent generations. The second generation gains are whittled down to just under 10% at a return of 680 fish, and by the fifth generation those gains are down to only 4% with a return of 797 fish.

After 10 generations, returns to our mythical river have only bumped up to 880 fish, and the hatchery's boost to total production has diminished to only 1%.

After 20 generations it more or less reaches a steady state at a return of 915 fish with a marginal gain of 0.1%, or about one fish per generation.

Not much of a gain after 20 generations... and at what cost?

And even if the hatchery were to quit while it was still reasonably ahead... at say, the fifth generation... the production from those 797 fish returning in the next generation would only be 577 fish. That's because the 100 wild fish that are no longer taken for broodstock would only produce 80 natural recruits instead of 300 hatchery recruits.

So even with the benefit of a remarkable recruit ratio of 3:1, running this hypothetical conservation hatchery for a time-limit of five generations would only yield 77 additional fish to the return after the hatchery ceases operations.

That's the nuts and bolts of it folks.

Again it will be up to managers to decide whether that type of investment is really worth it. For me it really all depends.

Getting back to my medical analogy with the critically ill cardiac patient in the ICU. Let's say what he really needs for a cure is a heart transplant. Spending $10,000 bucks a day on extraordinary life support to keep him on the ventilator, pacemaker, pressor drugs, and tube feedings would be reasonable.... but only if you were certain a donor heart was soon on its way.

Pretty pointless if it's not.