Little is known about the elusive Ganges river shark (Glyphis gangeticus), and what is known is mostly gathered from just three 19th-century museum specimens. Listed as critically endangered, the rare freshwater fish hasn’t been spotted in more than a decade. That is, until now.
Recently released photographs show a 2.6-meter (8.7-foot) female shark at a Mumbai fish market. The pictures were gathered as part of a study conducted under a Save Our Seas Foundation grant. The findings, published in the Journal of Fish Biology, are a result of nearly two years’ worth of weekly shark landing sampling, in which researchers recorded, interviewed, and measured sharks fished and traded at the Sassoon Docks.
Photographed in February 2016, the female shark was identified by researchers based on her round snout, small eyes, and fin characteristics specific to the species. However, researchers weren't able to collect morphological measurements or tissue samples because of “rapid processing of fishers and traders at the site.” They’re also not sure where the shark was caught, but speculate it could have been somewhere along the northeast coast of the Arabian Sea.
It’s not only the first confirmed sighting in more than a decade, but it’s also the first field observation of a whole species – the other available accounts come from just six jaws collected by Pakistani fishermen and traders.
“There are so few specimens of river sharks from around the world that pretty much all the information we have is based on either preserved specimens from the last century, or from jaws that were found at some point in remote villages and were identified as river sharks,” Rima Jabado, founder of the Gulf Elasmo Project, told New Scientist.
The “highly threatened, rare and elusive” shark’s distribution and status have been difficult to determine both globally and locally due to a lack of specimens. Much of what scientists know about the shark is extrapolated from its Australian cousin. Scientists do believe that the shark relies both on river and marine environments, both of which are heavily impacted by human development and habitat degradation.
One of 10 species of cartilaginous fish called Chondrichthyes that are protected under the Indian Wildlife (Protection) Act, the IUCN is not sure to what extent protection is enforced and cites concerns with compliance. Researchers say overfishing is likely an area of concern; in the last 30 years, India has consistently been among the top three largest catchers of sharks and rays in the world.
“Landings such as this record represent a conservation issue and mitigation measures should be considered urgently in view of the suspected low population sizes,” say the authors.