The rampant spread of catfish, known locally as African Mushi, in the waterbodies of the Wayanad Wildlife Sanctuary (WWS) is posing danger to the native aquatic species of the sanctuary, which is already facing threat from the wild growth of alien species of plants, including Senna spectabilis.
Though the sighting of catfish had been reported in waterbodies of the district, including major rivers, this was the first time that it was reported in the sanctuary.
“When we planned to organise a survey to make a checklist on the presence of indigenous fish species in the waterbodies of the sanctuary as part of World Biodiversity Day, some tribespeople informed me about the presence of the invasive species of fish inside the ponds of the sanctuary,” warden S. Narendra Babu told The Hindu.
In a sample survey conducted in two waterbodies in the Muthanga forest range, the frontline staff collected 73 catfishes, weighing 50.5 kg, said Mr. Babu. “There are 217 waterholes inside the sanctuary, including check dams, spread over four forest ranges and we are planning to conduct a survey in all the waterholes in the coming days,” he added.
It was suspected that the unprecedented floods over the past two years in the district might have facilitated the introduction of the aquatic invasive alien species into the new habitats, said Mr. Babu. The phenomenon endangered ecosystems, habitats and native aquatic species of the sanctuary, which was already facing threat from the rampant growth of invasive plants such as Mikania micrantha, Lantana, and Eupatorium, he added.
Researchers said that during heavy floods, invasive alien fish which were illegally farmed in fragile systems, including domestic aquarium tanks, ponds, lakes and abandoned quarries, escaped from captivity and entered nearby wetlands. After a while, they slowly began to wipe out local varieties by altering the functions of the ecosystem.