Uncertainty and Decision-making for Species-at-Risk Assessments in Canada

Abstract

This thesis investigated how uncertainty affects assessments of species’ extinction risk. Data from 374 vertebrate species assessments were input into a decision-making algorithm that emulated assessment methods for identifying (1) whether DUs could be validated based on an empirical test of ‘evolutionary significance’, (2) how expert opinion influenced threat status, and (3) how ecological uncertainty influences risk assignment and the use of expert opinion. Most DUs did not qualify as ‘significant’ designatable entities. Species with higher ecological uncertainty were more likely to be up-designated in light of expert opinion; the opposite pattern obtained for the rest. Current approaches of defining DUs and addressing uncertainty in risk assessments are unlikely to produce repeatable results, which has the potential to compromise reliability and transparency. Efforts to reduce reliance on qualitative criteria, and to directly incorporate methods to deal with uncertainty into assessment protocols, could improve reliability and confidence in species assessments.