One of India’s most famous fish could disappear before it even has a name.
Technically the humpback mahseer already has a name, just not a scientific one as established by a formal description in research literature. The giant carp—one of the world’s largest freshwater fish—was first described by scientists back in 1873 but it hasn’t been rigorously studied since then. In fact, scientists know so little about the 17 (or so) species of mahseer that live throughout south Asia that the group’s entire taxonomy is currently under revision so most of their old scientific names have been thrown out.
The question is, will those species live long enough to see their new names officially published? Research in the past five years has indicated that at least four mahseer species in south Asia are already endangered.
A new paper published May 13 in Endangered Species Research brings word that the humpback mahseer of India is even worse off than many of its relatives: It is now so rare that it may disappear within a generation.
Seeds for the species’s disappearance were sown decades ago by the very anglers who loved to fight to pull the muscular fish out of their only habitat, the Kaveri (aka Cauvery) River. Over the years too many of the massive fish were caught and the population plummeted.
As a result, Indian fisheries departments started breeding mahseer in captivity and releasing them into the river. They just made one mistake: The fish they bred looked like the humpbacks when they were young but they were actually another mahseer species—the much smaller blue-finned mahseer (which also now lacks a scientific name). “This is clearly a conservation program which has backfired,” the study’s lead author, ecologist Adrian Pinder of Bournemouth University in England, said in a prepared statement.
Pinder first saw evidence of the species mismatch when he traveled to India to fulfill a boyhood dream. “This research all stems from my interest as an angler, when as a boy I had read about this great fish,” he said. “In 2010 I made my first trip the River Kaveri, where I realized the fish I was catching did not match the appearance of the iconic specimens I'd seen in historic photos.” Instead of the 50-kilogram fish he expected, Pinder caught fish that weighed as little as 2.25 kilograms. Those were hardly the majestic creatures he had set out to find.
That disappointment led Pinder and biologist Rajeev Raghavan of India’s Saint Albert’s College to launch an international collaborative effort to better understand all of south Asia’s mahseer species. Along with the most recent paper, their work yielded three earlier papers and the establishment of the Mahseer Trust, a non-governmental organization devoted to the fishes’ conservation.
Pinder and his associates have returned to Kaveri multiple times to gather data since his first visit, and the findings are not good. A full 95 percent of the mahseers observed were of the smaller, blue-finned variety. “Our studies over the last two years have shown that they are now one of the most abundant fish in the river,” he said. “Without a doubt, their success has been at the expense of the humpbacked mahseer that historically occurred throughout the entire river catchment.” The paper theorizes that the blue-finned variety reproduce faster, mature younger (so they can breed even more) and make use of habitat resources more efficiently than the massive humpbacks.
Now Pinder and the trust are racing to save the humpback mahseer. He hopes to collect specimens, gather DNA evidence to allow the researchers to identify how it is related to its sister species and therefore rename it. Along the way, they also hope to get the fish officially listed as critically endangered and create a species survival plan.
None of those steps require the species to have a new name but the lack of scientific consensus on the taxonomy of all mahseer species slows down any efforts to conserve them. “The state of confusion surrounding mahseer taxonomy means the humpback mahseer currently lacks a valid scientific name and could potentially go extinct before being named,” he said. If that happens, it may only remain in the history books and in anglers’ dreams.
Photo courtesy of Bournemouth University