Research Document - 2015/015

Design of Ecological Risk Criteria for the Integrated Management of Canadian Oceans

By Jonathan A. Freedman and Derrick T. de Kerckhove

Abstract

Ecological risk criteria (ERC) are used in Canada and around the world within risk assessment and management frameworks.  The purpose of this Research Document is to evaluate and compare ERC risk categories and thresholds for use within the context of DFO’s ecosystem-based integrated oceans management (IOM) plan.

In particular, we investigated how DFO’s 2006 ERC were aligned with existing categories and thresholds used within other existing frameworks, and the biological significance of each criterion.  Within that context, we asked:

1. How realistic is it to compartmentalize spectrums of risk into separate categories and thresholds; and,
2. For nationally applicable ERC, how do we assign risk categories and thresholds that are general enough to be applied across a wide range of situations, geographic locations and scales, timings and human activities, yet specific enough to address complex ecological responses to environmental pressures?

Review of existing ERCs founds a range of appropriate models, with the majority consisting of three or five categories.  Both three and five category ERCs generally had a “low” or “negligible” risk category and a “high” or “intolerable” risk category, with 1-3 intermediate categories of increasing risk levels.  The number of intermediate categories was based on management outcomes, and perhaps on the accuracy and precision of available data. Thresholds among levels were often context dependent, and based on regional baselines or benchmarks.  In some cases (such as certain contaminants, e.g., mercury), however, predefined thresholds were used.  Given natural variations, in some cases there was difficulty determining at what point thresholds become too uncertain to be helpful.

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