The Red List assessment identifies biotopes, habitats and biotope complexes that are under threat of collapse. The threat is assessed based on decline in quantity or quality of the biotope. The Red List criteria identify threshold values for the decline and places the biotope in a threat category.
The goal of the HELCOM Red List II project was to assess the status of red-listed species and habitats/biotopes in the Baltic Sea, building on the results and insights from the previous HELCOM Red List project completed in 2013, following the Red List of Ecosystems Guidelines of the International Union for Conservation of Nature (IUCN).
A core principle of the project was to prioritize a data-driven approach over expert opinion in the assessments. This was intended to ensure objectivity, reproducibility, the ability to quantify trends, and the capacity to track changes over time – all crucial elements for a credible and effective Red List assessment. These data-driven principles were intended to strengthen the assessment’s impact on conservation policy and management. Due to data deficiencies the scope and number of biotopes that could be assessed were greatly reduced and decrease the evidence-base created in the project. The resulting reliance on expert opinion, while valuable, introduces a degree of subjectivity that the project initially aimed at minimizing. This data gap highlights the critical need for enhanced monitoring efforts and data collection across the Baltic Sea to support future, more robust Red List assessments. The limitations imposed by data scarcity should be noted and considered when using the current assessment’s findings.
HELCOM Red List threat assessment of habitats and biotopes uses the categories described in the IUCN Red Lists of Ecosystems Categories and Criteria.
