Expert judgement is often used to mitigate the knowledge gaps that limit understanding of aquatic non-indigenous species (ANS) impacts (consequences) to environmental, economic, social, cultural and human health values. To understand how this uncertainty may affect expert decision making, we explored the presence and effects of uncertainty on consequence assessment for 10 ANS by scientists and managers. We hypothesized species' distribution, taxonomy and impact type will affect assessment magnitude. These hypotheses were partially supported. We also hypothesized a difference in the relationship between consequence magnitude and uncertainty, based on assessor group. This set of hypotheses was not supported, as all group assessments had a significant negative correlation between consequence and uncertainty. Both scientists and managers assigned lower consequence when faced with knowledge gaps and other forms of uncertainty. This aligns with an "innocent until proven guilty" or hindsight approach, as opposed to a "guilty until proven innocent" or precaution approach. Based on these outcomes, the experts appeared to make decisions in violation of both the maximin principle and precaution, instead using a heuristic approach. We suggest several management strategies to prevent biases against environmental protection that occur due to use of the hindsight approach. © 2013 Elsevier Ltd.

Item Type:	Refereed Article
Research Division:	Studies in Human Society
Research Group:	Policy and Administration
Research Field:	Environment Policy
Objective Division:	Environment
Objective Group:	Environmental Policy, Legislation and Standards
Objective Field:	Coastal and Marine Management Policy
Author:	Dahlstrom, A (Ms Alisha Dahlstrom)
Author:	Campbell, ML (Associate Professor Marnie Campbell)
Author:	Hewitt, CL (Professor Chad Hewitt)
ID Code:	88101
Year Published:	2013
Web of Science® Times Cited:	4
Deposited By:	NC Marine Conservation and Resource Sustainability
Deposited On:	2014-01-13
Last Modified:	2014-05-22
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