Indian Freshwater Elasmobranchs: Ongoing Threats along with IUCN Current Status and Conservation of Protecting Hidden Treasures: A Review

Abstract

We always thought that elasmobranchs inhabit marine environments, but this is only partially true. About 5% of known elasmobranch species are the freshwater compared to 40% of teleost species. A systematic checklist is available for Indian freshwater elasmobranches with names and IUCN status. A total of 13 species belonging to 3 orders, 3 families and 10 genera were enlisted from secondary data. Euryhaline and obligate species include sharks as Carcharhinus, Glyphis (Carcharhinidae), Chiloscyllium (Hemiscylliidae), sawfishes or Pristis (Pristidae), stingrays or Himantura (whiprays) and Pastinachus (cowtailed rays) (Dasyatidae). We focus on distribution, feeding habits, threats and conservation. Freshwater excursions are relatively rare in extant elasmobranchs than other groups of fish. The low growth rate is probably due to late age at maturity and low fecundity, long gestation periods, slow growth and productivity (small, infrequent litters), high natural survivorship for all age classes and long life. Despite this, some species of freshwater elasmobranchs can tolerate and even thrive in freshwater.