What are the pros and cons of releasing captive-bred individuals of a species into an existing population of that species or into a vacant habitat where the species once occurred?

Question

(Assume that the existing population is below the carrying capacity of the habitat and that the conditions that were responsible for the extinction of the species in the vacant habitat no longer exist.)

Answer 1

This is an open-ended question, despite our effort to focus it by including the assumptions. We are trying to address genetic diversity and disease transmission: (1) Captive breeding populations are usually small and often inbred. Thus a genetic perspective suggests that augmenting an existing population is the better choice because the existing population is genetically different from the captive-bred individuals. (2) Introducing new animals to an existing population carries the risk of introducing pathogens despite stringent efforts to ensure the health of the captive-bred individuals. On that basis introducing the captive-bred individuals into the vacant habitat is the more prudent option.