Abalones at risk: A global Red List assessment of Haliotis in a changing climate

or (e) effects of introduced taxa, hybridization, pathogens, pollutants, competitors or parasites. Other criteria codes (B-E) are structured in a similar fashion being summarised at www. iucnredlist.org/resources/summary-sheet. In fulfilling such categorisation, it is assessed as threatened, i.e. CR, EN or VU, depending on the percentage reduction over the longer of ten years or three generations. Method of assessment We followed IUCN Red List standards that requires all assessments be based on data that are currently available for taxa across their entire global range. The primary means of collecting data on abalone species was through comprehensive literature searches in scientific journals and fishery and trade publications, together with specialist reports on regional catch statistics, wildlife crime, aquaculture, abalone ranching and restoration projects. National and regional fishery authorities periodically publish abalone catch quotas and stock assessments and, together with fishery statistics and analyses of catch data, provided essential data in determin- ing population trends. We consulted malacologists, fisheries managers, and international deal- ers in mollusc shells, as well as marine conservationists and experts in illicit wildlife trade through telephone and online conference calls, workshops, email, and web-based discussions, and analysing monitoring datasets to determine population trends (www.iucnredlist.org/ assessment/process). All data was transferred to the IUCN online assessment database–SIS.

To ensure all species’ assessments use the same classification system for threats, habitats, etc. SIS uses a standardized format for managing assessment data, in addition to ensuring Table 2. The five criteria. Criterium Parameter A Population size reduction, i.e., trend B Decline and/or fragmentation of extent or area of occupancy or habitat C Small population size with a continuing decline or fluctuation in mature individuals D Very small or restricted population E Quantitative analysis with a probability of extinction over a defined period https://doi.org/10.1371/journal.pone.0309384.t002 Table 1. The nine categories. Category Code Test Extinct EX There is no reasonable doubt that the last individual has died measured over a time frame appropriate to the taxon’s life cycle and life form Extinct in the Wild EW The taxon is known only to survive in cultivation, in captivity or as a naturalized population(s) well outside the past range Critically Endangered CR The taxon meets any of the criteria A to E for Critically Endangered, and it is therefore considered to be facing an extremely high risk of extinction in the wild Endangered EN As CR but considered to be facing a very high risk of extinction in the wild Vulnerable VU As CR but considered to be facing a high risk of extinction in the wild Near Threatened NT The taxon has been evaluated against the criteria but does not qualify for CR, EN or VU now, but is close to qualifying for or is likely to qualify for a threatened category in the near future

Least Concern LC The taxon has been evaluated against the criteria and does not qualify for CR, EN, VU or NT. Widespread and abundant taxa are included in this category Data Deficient DD There is inadequate information to make a direct, or indirect, assessment of the taxon’s risk of extinction based on its distribution and/or population status Not Evaluated NE The taxon has not yet been evaluated against the criteria https://doi.org/10.1371/journal.pone.0309384.t001 PLOS ONE Abalones at risk: A global Red List assessment of Haliotis PLOS ONE | https://doi.org/10.1371/journal.pone.0309384 December 23, 2024 6 / 25