The moral dilemma posted by Patrick McCusker on Black-footed Ferrets (The Black-footed Ferret – and the moral issue) is pretty well unsolvable, and I won't attempt it. But there is another issue that this could illustrate.
The Black-footed Ferret (Mustela nigripes), the Steppe Ferret (M. eversmanni) and the European Polecat (M. putorius) are all closely related, and could almost be considered part of a holarctic cline. The Steppe Ferret and the Black-footed Ferret not only look very similar, but also have very similar feeding habits, and other behavioural traits. The Black footed Ferret colonised North America along with many other elements of the fauna when Beringia linked North America to Siberia.
When a species is ecologically, genetically, and behaviourally very similar, might it not make more sense to boost the population by the introduction of some new blood from another population? Afterall, by the time the Black-foots were taken into captivity inbreeding was clearly a major concern.
I realise that this is a conservation heresy I am suggesting, but bearing in mind the millions of dollars programmes such as the Black-foot breeding soak up, and how limited funding is, surely it should be considered.