Perception and consideration of cumulative effects and multiple stressors by marine managers in Canada

The cumulative effects of multiple stressors are a pressing global concern for marine ecosystems. The effectiveness of marine management can be improved by considering three key elements that can affect their impacts: stressor interaction types, non-linear stressor–effect relationships, and ecosystem tipping points. Little is known about the degree to which cumulative effects, or these key elements, are considered in marine management in Canada. We surveyed Canadian federal government managers involved in managing either marine conservation areas or commercial fisheries, and asked (1) if they currently assess cumulative effects in decision-making, (2) if so, how and which elements are considered, and (3) the perceived importance of considering the three key elements. We also compared approaches among federal departments, management type, oceans, experience levels, and position types. We found that most managers (84%, n = 80) consider cumulative effects in decision-making. Responses clustered into either a structured approach, which included using an assessment framework and considering the three key elements of cumulative effects, or an intuitive approach, characterized by the absence of a formal framework or consideration of key elements. Neither was strongly linked with demographic categories. Despite most managers (97%, n = 37) believing that the three key elements of cumulative effects are important to consider, only 21% actually did so in decision-making. This discrepancy appears to be underpinned by barriers such as a lack of guidelines for assessing cumulative effects and data quality, quantity, and availability. We provide recommendations to overcome these challenges.