KARACHI: Tonnes of fish were found dead floating on a large Karachi Port Trust area on Monday morning.

People were seen collecting the dead fish mainly comprising mullets (called boi in local parlance), in the Karachi harbour, Manora channel and Chinna Creek early morning.

A large quantity of fish was reportedly sold to factories manufacturing fish meal (mainly used as poultry feed).

According to some estimates, the fish was about 100 tonnes of which 30 tonnes was already taken out and sold when reports of the mass death started pouring in. Many fishermen involved in collecting fish were engaged by the Karachi Port Trust for a “clean-up operation”.

According to experts, the incident occurred when the Lyari River, swelled with the rainwater, brought highly toxic chemicals from the Sindh Industrial Trading Estate (SITE) to the Karachi harbour area.

“This is not the first case of mass deaths of fish in the Karachi harbour area. The chemicals being released by industries located in the SITE area have caused fish mortalities on a large-scale many times. Industrial pollution discharged through the Lyari River has to be tackled at point source with the active involvement of all stakeholders,” Mohammad Moazzam Khan, technical adviser (marine fisheries) working with the World Wide Fund for Nature-Pakistan, said.

Mr Moazzam said that though the nutrient-rich rainwater resulted in higher productivity of the coastal area, such water turned heavily toxic when it passed through an industrial area and thus caused fish mortality.

“Because of heavy pollution, major parts of the Karachi fish harbour (receiving sewage through the Lyari River) and Gizri Creek (receiving sewage through the Malir River) have already turned in azoic zones where no life exists,” he said.

Rab Nawaz, director of the WWF-Pakistan, stressed the need for a comprehensive master plan for controlling pollution resulting from the discharge of industrial and domestic waste through Lyari and Malir rivers.

“About 435 million gallons of sewage is daily released through these two rivers, causing high level of pollution around Karachi. The city has a very limited capacity for sewage treatment, about 75MGD per day (provided sewage treatment plants operate at their installed capacity). It means 85pc of sewage is dumped directly into the sea without any treatment. This is devastating our marine flora and fauna,” he said.

Expressing concerns over the selling of dead fish, he said that whether the dead fish was used in fish meal or directly sold in the market both ways it carried hazards for human health.

Khalid Mahmood, co-principal investigator at the WWF-P who surveyed the area, said that the mortality of mullets, sea bream and skate fish had occurred around Baba Island which was located in the middle of lower harbour of Manora channel.

“The high tides took the fish to Chinna Creek, Native Jetty and Bhatta village area. The KPT has carried out a clean-up operation with the help of local fishermen who have removed about 35 tonnes of small-sized mullet, sea bream and skate fish from the area. These fish are considered important commercial species which are relished by local fishermen community,” he said.