Expected demographic and genetic declines not found in most zoo and aquarium populations

Abstract

Since the 1980s, animals in accredited zoos and aquariums have been managed as populations through cooperative breeding, with a goal of maintaining ex situ populations that are as demographically viable and genetically diverse as possible. Here, we provide what we believe to be the first large-scale assessment of whether cooperative breeding programs are achieving this goal over time. Using a comprehensive dataset spanning nearly 20 years and encompassing more than 400 ex situ vertebrate populations, we applied Bayesian hierarchical modeling to quantify changes in seven population metrics over time. Instead of the general declines expected for small and often closed populations like those in zoos and aquariums, we found no change in the demographic and genetic characteristics of the majority of these populations. Our results indicate that while some zoo and aquarium populations are currently unsustainable, cooperative management is helping to slow or prevent declines in the health of many ex situ populations.