High pollution levels, has led to a 70% decline in native fish species in Powai Lake over the past two decades. Environmentalists also blame the overpopulation of invasive fish species.
According to a recent study, by Powai-based non-profit organisations only 10 native fish species present in the lake. The study was carried out at the 2.1-sqkm area of the lake. According to the earlier day it was confirmed that 37 species recorded in the lake, in 1990.
“The introduction of a number of non-native species such as the African magur, Mozambique tilapia, Arapaima, alligator gar and another 20 such aquarium species have altered the food chain,” said Ali Husaini, president, AIGFA.
Ali further mentioned that based on their results, the magur species of fish, is the most predacious of all other foreign species.
Native species such as the mahaseer, chilwa, four species of putnis, barramundi have gone missing, and those such as catla, rohu, mrigal, grass carp, sneakhead or murrels, spiny eel and others continue to survive in the lake.
The survey was carried out by Naushad Ali Sarovar Samvardhini (NASS), All India Game Fishing Association (AIGFA) and the Maharashtra State Angling Association (MSAA). According to MSAA, Powai Lake was created by the British in 1890 by constructing two stone dams on the Powai rivulet.
To increase the count of native species, MSAA introduces 10,000 mahaseer and 10 lakh Indian carps into Powai Lake every few years from Aarey hatcheries and other sources across India. “The fish, however, do not breed owing to water pollution that has led to a loss of oxygen at the lake,” said Husaini.
“Other problems such as siltation, low fertility and over fishing are some other reasons that have led to their declination,” he added.