River shark

Glyphis is a genus in the family Carcharhinidae, commonly known as the river sharks. They live in rivers or coastal regions in and around south-east Asia, Africa and parts of Australia.

Taxonomy

This genus contains only three extant species. Further species could easily remain undiscovered due to their secretive habits.<ref name=pmid26460025>Template:Cite journal</ref> This genus was thought to contain five different species, but recent studies on molecular data revealed that the species Glyphis gangeticus has an irregular distribution in the Indo-West Pacific region.<ref>Template:Cite journal</ref> The genus Glyphis is closest to the genus Lamiopsis.

Species

The recognized species in this genus are:<ref>Template:Cite WoRMS</ref>

• Glyphis fowlerae Compagno, White & Cavanagh, 2010 (Borneo river shark) synonym of G. gangeticus<ref name=pmid26460025/>
• Glyphis gangeticus (J. P. Müller & Henle, 1839) (Ganges shark)
• Glyphis garricki L. J. V. Compagno, W. T. White & Last, 2008 (northern river shark)
• Glyphis glyphis (J. P. Müller & Henle, 1839) (speartooth shark)
• Template:ExtinctGlyphis hastalis Agassiz, 1843<ref name=FW/>
• Template:ExtinctGlyphis pagoda (Noetling, 1901)
• Glyphis siamensis (Steindachner, 1896) (Irrawaddy River shark) synonym of G. gangeticus<ref name=pmid26460025/>

Distribution and habitat

Their precise geographic range is uncertain, but the known species are documented in parts of South Asia, Southeast Asia, New Guinea<ref name=P1>Template:Cite journal</ref> and Australia. Of the three currently described species, the Ganges shark is restricted to freshwater, while the northern river shark and the speartooth shark are found in coastal marine waters, as well. While the bull shark (Carcharhinus leucas) is sometimes called both the river shark and the Ganges shark, it should not be confused with the river sharks of the genus Glyphis. River sharks evolved to have their offspring in freshwater, therefore, making them safe to roam in the water while other sharks are able to survive in saltwater.

Conservation

River sharks remain very poorly known to researchers. River sharks were thought to be extinct until the end of the 20th century, when small populations were discovered in Borneo and Northern Australia.<ref>Template:Cite journal</ref> Now, they face a critically endangered status as they are so poorly studied, and people know very little about their population and life history.

Glyphis gangeticus uses the Ganges River as nursery grounds and the birthplace of many Ganges shark offspring, however the population has been severely diminished owing to a long history of fishing and other pollution-related issues in the Northern Arabian Sea. Additionally, India, where the Ganges river flows, is reported to be one of the top three greatest shark and ray capturers in the world, accounting for up to nine percent of reported global landings (Jabado et al., 2018). They are reported from the Zambezi river in Africa. They have been found in nine different tidal areas, which consist of muddy waters with a low salinity. Their placement in connection to coastal marine waters indicates that they are usually born around October.<ref name="P1" />

Images

• Ganges shark (G. gangeticus)
  Ganges shark (G. gangeticus)
• Northern river shark (G. garricki)
  Northern river shark (G. garricki)
• Speartooth shark (G. glyphis)
  Speartooth shark (G. glyphis)