Estimates of temporal trends in species’ occupancy are essential for conservation policy and planning, but limitations to the data and models often result in very high trend uncertainty. A critical source of uncertainty that degrades scientific credibility is that caused by disagreement among studies or models. Modellers are aware of this uncertainty but usually only partially estimate it and communicate it to decision-makers. At the same time there is growing awareness that full disclosure of uncertainty is critical for effective translation of science into policies and plans. But what are the most effective approaches to estimating uncertainty and communicating uncertainty to decision-makers? In this study we explored alternative approaches to estimating and communicating trend uncertainty arising from ensemble models of species trends. All approaches were designed to fit an established decision-making system used to assign species conservation status by the New Zealand government. We show how approaches that fail to fully disclose uncertainty, while simplifying the information presented, can hamper species conservation and/or lead to ineffective decisions. We recommend an approach that was recently found to be effective for communicating trend uncertainty to a panel responsible for setting the conservation status of New Zealand’s freshwater fishes. We discuss how this approach is particularly important for robust decision-making on rare or data-limited species.