Few zoo Species Survival Plans are genetically sustainable over 100 years

A 2009 assessment of more than 500 AZA Species Survival Plans (SSPs) concluded that few programs were estimated to be genetically and demographically sustainable over a 100-year timeframe. Population geneticists recommend an effective population of 250-500 individuals as the minimum to avoid steady genetic drift and inbreeding, but most zoo populations fall far below this threshold. This matters because SSPs are the primary justification zoos offer for keeping endangered species in captivity — the promise that they are maintaining a viable 'insurance population' against extinction. If these populations are not genetically sustainable, then the conservation argument collapses: zoos are maintaining shrinking gene pools that will eventually become too inbred to serve as reintroduction stock. The problem persists because zoo exhibit space is finite, inter-zoo animal transfers are logistically expensive and stressful, and some institutions resist SSP breeding recommendations that conflict with their own exhibit plans or visitor appeal. Additionally, there are now 295 SSPs competing for limited space, meaning each individual program gets fewer slots than it needs.