‘Forgotten fauna’: Little known river sharks and rays face increased extinction risk

Fishers on India's Vashishti River hauled up three bull sharks in 2023, the first documented sharks from that river, spotlighting how little is known about sharks and rays living in rivers and estuaries worldwide. Researchers say about 60 species spend part of their lives in inland waters, and 76% of non-marine elasmobranchs in the Indo-Pacific are threatened with extinction, roughly double the rate for all sharks and rays globally.

Scientists cite dams, mining, pollution, overfishing and climate-driven changes to river flows as the main threats, compounded by the fact that many species are only known from a handful of records. In South America, freshwater stingrays face additional pressure from the aquarium trade, where wild-caught individuals remain in demand despite captive breeding programs.

Researchers in Brazil, Australia and elsewhere say a single dam or heavily fished stretch of river can wipe out an entire population of species confined to narrow habitats, and are calling for more basic research before more species disappear unrecorded.

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