Polluted lake and foreign fish drown the natives: Survey

NATIVE FISH SPECIES STILL SURVIVING AT THE LAKE

MUMBAI: High pollution levels, along with overpopulation of invasive fish species, has led to a 70% decline in native fish species in Powai Lake over the past two decades.

This could be the reason for some creased eyebrows in the near future because this will affect the food chain, which will disturb the larger picture — the ecosystem.

A recent study carried out at the 2.1-sqkm lake by Powai-based non-profit organisations found only 10 native fish species present in the lake, compared to 37 species recorded 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 species have altered the food chain,” said Ali Husaini, president, AIGFA, adding the magur is the most predatory of all other foreign species.

Native species such as the mahaseer, chilva, 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).TO increase the count of native species, MSAA introduces 10,000 mahaseer and 10 lakh Indian carps into Powai Lake every few years. “The fish do not breed owing to water pollution that has led to a loss of oxygen at the lake,” said Husaini.

Officials from MSAA said that unidentified people have been releasing goldfish at the lake, which is predominantly an aquarium fish. There are instances of such migrations across the world too. During the 1990’s, the snakehead, a fish native to Africa and Asia, (also spotted at Powai Lake) has been detected in the United States, where it is highly invasive. Scientists fear a significant threat to aquatic ecosystems and native species such as crabs and clams due to their introduction by catfish farmers across USA.

“Suppliers sending us fish, which have been spawned at ponds with invasive fish species, inadvertently find their way to the lake,” said Rodricks. Catla catla (Catla)

Labeo rohita (Rohu)

Cirrinus mrigala (Mrigal) Labeo calbasu (Calbasu) Osphronrmus goramy (Gouramy) Ctenopharyngodon idella (grass carp) Hypophthalmichthys molitrix (Sliver Carp) Channa argus

(Snakehead Fish or Murrels) Cyprinus carpio (Common Carp) and Macrognathus (Spiny Eel).

THE MISSING SPECIES Mahseer, Puntius, Barramundi, Chilva