Linked decisions and uncertainty in ex-situ conservation plannin

Background/Question/Methods

Ex-situ conservation strategies for endangered species can be complex, expensive and prone to failure. Since they often involve long-term commitments of limited resources, managers need to carefully consider the decision of whether to implement ex-situ management as part of species recovery plans.

Here, we interpret this decision as the end point of several linked decisions, and present a general decision tree to approach these in the appropriate logical order. We argue the decision to implement ex-situ management can only be solved after a two-step assessment. First, defining clearly how the ex-situ population will be used (e.g., the optimal management of reintroduced individuals). Second, explicitly considering the stochastic and uncertain processes within the ex-situ program itself (e.g., the probability of successful breeding in captivity).

Using an on-going recovery program for an endangered frog species as an example, we demonstrate how ignoring the links between these decisions can lead to inefficient use of resources.

Results/Conclusions

We found ex-situ management actions were optimally cost-effective only under strong risk-seeking attitudes favouring highly positive results against much greater costs. Ex-situ actions became sub-optimal when their adoption reduced the effectiveness of in-situ management (for example by diverting resources), and when there were even moderate chances (>50%) of failure during the ex-situ establishment phase.

Our framework provides a rigorous, scalable method to capture the complexity of ex-situ planning and the logical structure of the required decisions. Its adoption can increase the transparency of recovery plans and help ensure rational and focused cooperation between conservation agencies and ex-situ institutions.