THATTA, May 2: The giant freshwater prawn and monsoon river prawn face threat of extinction because of high levels of pollution in the Indus waters and an acute shortage of water downstream Kotri Barrage, according to a study conducted by Prof Dr Wazir Ali Baloch of the Department of Freshwater Biology and Fisheries, University of Sindh.

Dr Baloch, who was on a visit to Thatta, told this correspondent that the study on prawns in the river along Kotri downstream carried out in collaboration with Sindh Fisheries Department from May to July 2010 did not find even a single specimen of giant fresh water prawn locally called Gangat or Sano.

However, he said, the fishermen talked about occasionally catching the rare blue prawn (probably giant freshwater prawn).

Natural decline of this species has also been reported from Bangladesh, India, Indonesia, Malaysia, the Philippines and Thailand and it is believed to be extinct in Singapore largely as a result of pollution, he said.

He urged the government to take measures for the conservation of Gangat. The species’ natural habitat is found in Pakistan, Vietnam, South East Asian countries and parts of Australia and Papua New Guinea.

The other species, the monsoon river prawn, was observed in upstream to downstream along 180 km stretch of the Indus. It is caught in comparatively high estuarine area and Thatta fish market is its main landing centre.

Dr Baloch said that during the study it was found that this prawn was being caught in the river near Tando Hafiz Shah, Raju Nizamani, Jherruck, Sonda, Chulh, Sonehri (Keenjhar), Hillaya, Khambho, Ranta Mianu, Saeed Pur (Left Bank), Aghimiani Kori, Ghorabari, Daulatpur Miano, Ahmed Khan Miano, Moosa Miano, Kori Khalifa, Jhangisar, Babiho Miano, Sajjan Wari Miano and Kharo Chann in Thatta district.

Fresh water habitats, he said, were on the decline because of shortage of freshwater, mismanagement or unawareness. The species could be conserved by producing seed artificially and culturing the prawns in captivity, he said.

In this regard, a study on seed production and larval development of monsoon river prawn is under way.

More studies on occurrence, life-cycle, reproduction, migration and identification of spawning grounds of both the threatened species in the Indus were needed to check their life-cycle in larval development, he said.

The information thus accumulated would help conserve the giant river prawn in the river and establish the culture of freshwater prawn in the country, he said.

Dr Baloch said that the Indus was a habitat of migratory fish Pallo (tenualosa), blind dolphin and many other crustaceans. All these creatures were facing threat of extinction because the habitat faced water shortage and deterioration of water quality, he said.

Keenjhar Fishermen Welfare Society Chairman Adam Gandhro said non-release of water downstream Kotri would minimize the expected benefits of floods along the Thatta coastline.

Enormous species, including prawns, required comparatively brackish water during their breeding period in and around mangrove forests, which too were depleting due to non-release of fresh water downstream, he said.

The situation, he said, was affecting shrimp sanctuaries and hatcheries in coastal area. Thatta district used to be a hub of shrimp catch but now its catch had declined to almost zero, he said.

He suggested that it be declared threatened species.