Extinction risk of the world's freshwater mammals.

The continued loss of freshwater habitats poses a significant threat to global biodiversity. This review quantifies the extinction risk of 166 freshwater aquatic and semi-aquatic mammals-a group rarely documented as a collective. The International Union for the Conservation of Nature Red List of Threatened Species categories were used as a measure of extinction risk to compare taxonomic groups, geographical areas and biological traits. Thirty percent of all freshwater mammals are currently listed as threatened. Decreasing population trends are common (44.0%), including a greater rate of decline (3.6% in 20 years) than mammals or freshwater species as a whole. Aquatic freshwater mammals are at a greater risk of extinction than semi-aquatic freshwater mammals (95% CI -7.20 to -1.11). Twenty-nine species remain data deficient or not evaluated, while larger species (95% CI 0.01 to 0.03) with greater dispersal distances (95% CI 0.03 to 0.15) have a higher risk of extinction. The number of ongoing threatening processes compound the risk of extinction (95% CI 0.28 to 0.77). Hunting, land clearing for logging and agriculture, pollution, residential development and habitat modification from dams and water management pose the greatest threats to these species. The basic life history traits of many species are poorly known, highlighting the need for more research. Conservation of freshwater mammals will require a host of management actions centered around greater protection of riparian areas and more conscientious water management to aid the recovery of threatened species. This article is protected by copyright. All rights reserved.