Global Patterns and Drivers of Freshwater Fish Extinctions: Can We Learn From Our Losses?

Area of Science:

• Conservation Biology
• Ichthyology
• Environmental Science

Background:

• Freshwater fish represent over 50% of global fish diversity, yet nearly one-third are threatened with extinction.
• The ecological and socioeconomic importance of freshwater fishes is immense, but their extinction is under-researched globally.
• Understanding extinction patterns and drivers is crucial for effective conservation of these vital species.

Purpose of the Study:

• To comprehensively assess taxonomic, spatial, and temporal patterns of freshwater fish extinctions.
• To identify key drivers of extinction and their synergistic effects.
• To evaluate current extinction rates against natural background rates and inform conservation strategies.

Main Methods:

• Analysis of 89 extinct and 11 extinct-in-the-wild freshwater fish from the IUCN Red List.
• Taxonomic statistical analysis to identify impacted families (e.g., Cyprinidae, Leuciscidae, Salmonidae).
• Calculation of extinction rates per million species-years (E/MSY) globally and continentally; Bayesian modeling for driver association.

Main Results:

• Modern freshwater fish extinction rate is 33.47 E/MSY, over 100 times the background rate (0.33 E/MSY).
• North America (225.60 E/MSY) and Europe (220.26 E/MSY) exhibit the highest continental extinction rates.
• Natural system modification, pollution, and invasive species are primary drivers, often acting synergistically, with accelerating trends since the mid-20th century.

Conclusions:

• Freshwater fish extinctions are accelerating despite conservation efforts, underscoring the urgent need for integrated strategies.
• North America and Asia show strong associations with species loss, while Europe has a moderate association.
• Without immediate, comprehensive action, many at-risk freshwater fish species may face extinction.