A benchmarking and assessment framework to operationalise ecological indicators based on time series analysis

Abstract

The call for ecosystem considerations in marine management has instigated the use of ecosystem indicators. Many ecosystem indicators have been suggested under new policy frameworks such as the EU Marine Strategy Framework Directive or the Common Fisheries Policy. But many of these indicators are still under development and cannot be considered as yet operational for environmental assessments. A common reason for this lack of operationability is the absence of valid assessment benchmarks. This study introduces a two-stage approach for the benchmarking and assessment of time series (TSBA) against a priori chosen rationale of improvement or maintenance of current conditions. TSBA uses breakpoint- and trend-analysis to obtain long-term benchmarks and assess short term progress. Depending on the outcome of both analyses the action requirements for management can be determined. The method is exemplified on a case study on the size-structure of large North Sea gadoid stocks, which are considered as being sensitive to the impacts of fishing. Three out of six stocks reached their assessment benchmarks, while the three other stocks failed. TSBA is generic and can be applied to any indicator used within any marine policy assessment framework. A strength–weaknesses–opportunity–threat analysis (SWOT) investigated the advantages and disadvantages of TSBA in the context of the currently high political demand of operational ecosystem indicators. Contrary to benchmarks derived from ecological concepts or pressure-state relationship TSBA benchmarks are not specifically linked to limits of resilience or sustainability. However, TSBA may be especially useful in situations where assessment benchmarks from other sources will not be readily available or are associated with high uncertainty.