The HELCOM Red List of Baltic Sea species in danger of becoming extinct (2013) was the first threat assessment for Baltic Sea species that covered all marine mammals, fish, birds, macrophytes (aquatic plants), and benthic invertebrates, and followed the Red List criteria of the International Union for Conservation of Nature (IUCN).
The goal of the HELCOM Red List II project was to assess the status of red-listed species in the Baltic Sea, building on the results and insights from the previous HELCOM Red List project completed in 2013, and using the updated HELCOM Checklist of Baltic Sea macro species 2.0.
The HELCOM Red List regional assessment uses nine categories: Regionally Extinct (RE), Critically Endangered (CR), Endangered (EN), Vulnerable (VU), Near Threatened (NT), Least Concern (LC), Data Deficient (DD), Not Applicable (NA) and Not Evaluated (NE).
The HELCOM Checklist 2.0 contains a total of 3 005 species. Based on available data a selection of 2 023 species or other assessment units were made and included in the assessment process. In regard to dividing species into assessment units below the species level (i.e. subspecies or distinguishable populations), the approach has varied between species groups in a few cases, and consequently the total number of considered assessment units can be counted in different ways. 1 445 species or other assessment units (71.4%) were assigned to a red-listing category according to the IUCN Guidelines, 95 of them (4.7%) were categorized as threatened (either CR, EN or VU) and 578 species or other assessment units (28.6%) were left unassessed (either as Not Evaluated or Not Applicable). 2013 Red List used the HELCOM first checklist (HELCOM 2012) with 2 730 species and the assessment project used altogether 2 791 listed species or other assessment units for the assessment process, out of which 1 753 were evaluated, 69 of them (3.9%) were categorized as threatened and 1 038 of them were left unassessed (either as Not Evaluated or Not Applicable).
The 2013 Red List assessment was done in a combination of data-driven assessment process and some expert opinion-based assessment. The 2024 Red List II assessment was done as a data driven exercise only with a lot more data available for the assessment process than in 2013. Thus, some of the results in this report show significant differences when comparing the 2013 and 2024 assessment results and trends in results and may be due to broader data availability than necessarily a change in status. In the 2013 Red List assessment process it was acknowledged the difficulty to make the division between Not Evaluated (NE) and Data Deficient (DD) and even Least Concern (LC) in many cases.
When comparing red list assessment results across different evaluations, it is important to consider the factors driving changes in assessment categories. These changes can stem from actions taken to improve a species’ status or from increased pressures, but they may also result from better knowledge or data availability. Consequently, as the number of evaluated species increases with the growing availability of data, it is possible that the proportion of threatened species may also rise in future HELCOM assessments (HELCOM, 2023).
In 2024 the category Not Applicable (NA) was assigned to those species that are freshwater species (not being a marine species) and to all non-native species that have been intentionally or unintentionally introduced after 1800.
HELCOM Red List II of Baltic Sea species in danger of becoming extinct