IUCN Red List
The world's main list of how close species are to extinction, kept by the International Union for Conservation of Nature.
Also: Red List of Threatened Species
The International Union for Conservation of Nature has run its Red List since 1964. Experts assess each species against set criteria, such as how fast it is declining and how small its range is, and place it in a category: Least Concern, Near Threatened, Vulnerable, Endangered, Critically Endangered, Extinct in the Wild or Extinct. Data Deficient means there is too little information to judge. Vulnerable, Endangered and Critically Endangered together count as threatened. Many fish have still never been assessed, and assessments can be years old.