An alarming surge of stinger jellyfish in the continental shelf along Pakistan coast has widely scaled down fishing operations during the last two weeks, the WWF-Pakistan said on Monday.
With deadly eight tentacle-stings, jellyfish continues to obstruct fishing sticking in the fishermen's nets from the continental shelf to the Sindh and Balochistan shorelines. The population of jellyfish has grown by over 150 individuals per cubic meter, it said.
According to WWF-Pakistan, "Large aggregations of this stinging jellyfish, which have mauve to magenta colour, are reported in offshore waters of Karachi to Swatch Area at the mouth of the River Indus (around 140 kilometre south of Karachi) and Ormara along Sindh and Balochistan coast."
Technical Advisor (Marine Fisheries), WWF-Pakistan, Muhammad Moazzam Khan said that jellyfish population was soaring exponentially along Pakistan seawaters and other parts of the world. "Such blooms disrupt the fishing industry by tearing and clogging nets," he said.
With fears, he said that jellyfish robust growth could scale back population of the commercially important fish species by eating their eggs, larvae and juveniles. He said that deadly jellyfish also feared to reduce the country's maritime tourism. "Jellyfish sting swimmers, therefore, may discourage tourism in some areas," he added.
Despite scores of evidences, he said that scientists advocated for more research in order to determine conclusively whether the jellyfish surge was a part of natural cycles or a result of human impacts on environment. He said that jellyfish were fed on plankton, crustaceans, small fish and fish eggs.
"It [jellyfish] depletes the food resources of fishes and even larger mammals like whales," he warned, saying that there was a need for research on causes of bloom formation by jellyfish.
Jellyfish is also commercially harvested in Pakistan as the country exports around 2,500 metric tons of dried jellyfish to the world markets, every year. Pakistan mainly trades in Rhopilemahispidum and Catostyluspereziare species of the jellyfish.
The country made the highest jellyfish export of 4,000 metric tons between 2005 and 2007, per year, mainly its different products to China and Vietnam. Jellyfish hunting is carried out from some 15 permanent and 35 temporary facilities along Pakistan shoreline, the WWF-Pakistan said. Major plants to process jellyfish are located in different areas including Ibrahim Hyderi, Rehri and Keti Bundar in Sindh and Damb along Balochistan coast. Its key harvesting sites are in Damb and Kalmat in Balochistan and creek areas of Sindh. Its main quantities are also harvested through nettings and gillnets.
Jellyfish catch provides an additional source of living to the poor and middle-calls fishermen in Pakistan. According to an estimate, over 10,000 people are engaged in jellyfish fisheries in Pakistan. The sudden rise of jellyfish was not first as the stinging species had also flooded the country's sea in 2002 that cause a slump in catch of seafood, the WWF-Pakistan said.
"Reasons for sudden increase in the population of some jellyfish and forming large blooms are not fully understood. It is generally believed that climate change and resulting warmer sea temperatures favour most jellyfish to increase in massive numbers resulting in blooms spreading in large areas."
Senior Director Programmes, WWF-Pakistan Rab Nawaz said.
He blamed that the overfishing had resulted in jellyfish population growth. "Discharge of untreated sewage loads in coastal waters with nutrients may cause eutrophication making available more food for jellyfish polyps and support forming of bloom.
Fishermen hunting with gillnetting and other modes have moved their operations to other parts mainly to Sonmiani Bay and adjacent seawaters. A sudden fall in fisheries catch of some prime seafood species is attributed to the jellyfish rise.
One of fishermen, Falak Niaz, whom the WWF-Pakistan has trained, said that "this luminescent bloom is spread over area of about 250 squares kilometres in the offshore waters but currently it is declining. Previously, such blooms in Pakistan were observed to last about 10 to 20 days. This is of no commercial importance of this jellyfish".
In further offshore waters near Swatch Area at the mouth of the River Indus, another bloom of mammoth jellyfish has been reported. The population of this large invertebrate species surged over the second week of December 2016 that continued till date. In some of the areas their numbers are too large that fishermen have halted their fishing operations.
"This jellyfish species is very large in size and its disentanglement from the net and throwing back in the sea is a cumbersome process and has to be done carefully due to its painful stings.