Troubled waters in the land down under: Pervasive threats and high extinction risks demand urgent conservation actions to protect Australia's native freshwater fishes

Abstract

We conducted the first comprehensive global assessment of the extinction risk of Australia's native freshwater fishes. Using International Union for Conservation of Nature (IUCN) criteria, 37 % (88 species) of the 241 assessed species were threatened (Critically Endangered, Endangered or Vulnerable), with one being Extinct. Lepidogalaxiidae and Neoceratodontidae had the highest level of threat (100 %, both single species families), followed by Galaxiidae (78 % of 40 species), Percichthyidae (62 % of 22 species) and Melanotaeniidae (53 % of 19 species). Northern Australia supported greater species richness, while a concentration of threatened species occurred in the more human-populated areas across southern and eastern drainage divisions, including South West Coast (55 % of species assessed as threatened), Tasmania (54 %) and South East Coast (Victoria) (45 %). Most threatened freshwater fishes qualified for listing based on their restricted geographic ranges (Criterion B: 70 % of all assessments; Criterion D2: 7 %) although population size reduction (Criterion A) was identified in 21 % of species assessments. Key threats to species included invasive and other problematic native species, genes and diseases (92 % of threatened, Near Threatened or Data Deficient species), natural system modifications (82 %), and climate change and severe weather (54 %). Despite the high level of extinction risk, implemented conservation measures for threatened species are presently very limited. A further 17 species were assessed as Near Threatened. This study highlights the imperilled nature of Australian native freshwater fishes and emphasises that targeted conservation measures are urgently needed to avoid imminent extinctions.