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Freshwater fish species globally are under grave threat according to the latest edition of the International Union for Conservation of Nature (IUCN)’s Red List.
In fact, over half of Japan’s endemic freshwater fishes and more than a third of freshwater fishes in Mexico were threatened with extinction, the list of threatended species released on July 18, 2019, said.
The main reasons behind this were the usual suspects, namely loss of free-flowing rivers and agricultural and urban pollution.
It was revealed recently that two-thirds of the world’s great rivers no longer flow freely.
Another noteworthy factor was competition with and predation by invasive alien species of fish.
“The world’s freshwater fish species, which number almost 18,000, are undergoing a dramatic and largely unrecognised global decline, as made apparent in the high levels of extinction threat to freshwater fish species in Japan and Mexico,” William Darwall, head of the IUCN Freshwater Biodiversity Unit, was quoted as saying in a press statement by the IUCN.
“The loss of these species would deprive billions of people of a critical source of food and income, and could have knock-on effects on entire ecosystems. To halt these declines, we urgently need policies on the human use of freshwaters that allow for the needs of the many other species sharing these ecosystems.”
According to experts, India's freshwater fish can still be saved
“There is no doubt that India’s freshwater fish species are declining,” Wazir Singh Lakra, former vice chancellor, Central Institute of Fisheries Education told Down To Earth.
“The declining of water levels, pollution and other factors are contributing to this. However, our species are not yet at the point of extinction. They still have a scope of recovery,” he added.
Lakra said that the best way to prevent the decline of India’s freshwater fish was to revive the country’s rivers.
“We just do not have the required amount of water in our rivers needed to sustain aquatic life. The biggest reason behind this is the construction of dams,” he said.
“In India, fisheries experts are not consulted for their advice before a plan to construct a dam is drawn up. Their advice is most important. If they can be consulted, it would mean a lot for freshwater aquatic life,” he continued.
According to Threatened Freshwater Fishes of India published by Lakra in 2010 with three co-authors, 120 species of Indian freshwater fish species were threatened out of which, 71 were endangered and 49 were vulnerable. The report was a publication of the National Bureau of Fish Genetic Resources, Lucknow, of which Lakra was the then-director.
"India has an incredible diversity of freshwater fish, including many found nowhere else on earth. Of these, there are several in the most threatened category of Criticality Endangered, particularly in the southern peninsula, and many that are currently not assessed, which makes them extremely vulnerable," education and outreach officer of the non-profit Mahseer Trust, Steve Lockett said. He works on the hump-backed Mahseer of South India.
He added: "The main threats to native fish is gross and illegal pollution, and the loss of river flow and habitat due to dam building. Also high up the list of threats are releases of invasive fish that bring potential diseases and over-compete for finite resources. Destructive fishing methods like use of poisons or dynamite not only harm fish, they also indiscriminately kill all wildlife and lessen the chances for future generations to sustainably harvest from rivers".
While agreeing with Lakra that river revival was crucial to save freshwater species, Lockett also highlighted the role of pollution and Indian laws.
"The best place to start is enforcing laws that are as strong as any in the world. Pollution is very costly to the economy. I have read that it costs $500 million a year in lost productivity due to illness. Fixing pollution could help threatened fish, help businesses and boost water supply to cities," he said.