Unusual jellyfish blooms affecting fishing activities in coastal areas

Unusual jellyfish blooms affecting fishing activities in coastal areas

KARACHI: Fishermen have reported extraordinary jellyfish blooms in the offshore waters of coastal areas of Sindh and Balochistan which are affecting fishing activities.

For the past two weeks, these blooms of mauve stinger, scientifically known as Pelagia noctiluca having shades from mauve to magenta, are being observed on the continental shelf along the Sindh and Balochistan coasts.

These huge blooms have been cropping up in the offshore waters from Karachi to Swatch Area at the mouth of the River Indus (around 140 kilometres south of Karachi) and Ormara along Sindh and Balochistan coast.

The WWF-Pakistan studies have revealed a population of more than 150 individual per cubic meter which is clogging the nets of the fishermen. Mauve stinger has eight tentacles which are loaded with stinging cells known as cnidocytes. Within these cells are harpoon-like structures full of venom, called nematocysts which stings when triggered by touching and can penetrate human skin. Jellyfish is locally known as "Langara" in Sindhi and "Mus" in Balochi.

Pelagia noctiluca is known for beautiful luminescence and glittering at night when disturbed or moved by wave action. Luminescence in sea has been reported by fishermen during the last two weeks. Due to the high density of this jellyfish, fishing activities are affected in these areas resulting in clogging of nets. In addition, handling or removing this jellyfish from the nets can inflict severe and painful stings.

Once affected, the pain lasts for more than 24 hours and results in inflammation of skin. Fishermen involved in gillnetting and other fishing operations have now moved to other areas, mainly to Sonmiani Bay and adjacent waters.

Sudden decrease in the catches of some prime fishes is being attributed to the jellyfish bloom.

Falak Niaz, a fisherman, said that the luminescent bloom is spread over an area of about 250 square kilometres in the offshore waters but now it is reducing. Previously, such blooms in Pakistan lasted about 10 to 20 days.

In the offshore waters near Swatch Area at the mouth of the River Indus, another bloom of mammoth jellyfish commonly called mushroom jellyfish (scientifically known as Rhopilema hispidium) has been reported.

The population of this large jellyfish surged during the second week of December and continued till filing of this report. In some areas, these were high in numbers and the fishermen had decided to halt their fishing operations. These jellyfish species are very large in size and their disentanglement from the net and throwing back in the sea is a difficult process and has to be done carefully due to their painful stings.

Jellyfish is also commercially harvested in Pakistan for exporting purposes. Annually about 2,500 million tons of dried jellyfish is exported.

Rhopilema hispidum and Catostylus perezi are two dominating species which are being processed and exported from Pakistan. Highest jellyfish export was observed during 2005 to 2007 when annually about 4,000 m. tons of jellyfish products were exported to China and Vietnam. There are about 15 permanent and about 35 part-time or temporary facilities along Pakistan coast where the processing plants are located . They are mainly in Ibrahim Hyderi, Rehri and Keti Bundar in Sindh and Damb along Balochistan coast.

There have been reports of large jellyfish bloom in Pakistan, however, in December 2002, a massive jellyfish bloom occurred all along the coast. Large number of Crambionella orsini have resulted in decreased catch of commercial fishing operations along the coast.

Muhammad Moazzam Khan, Technical Advisor (Marine Fisheries), WWF-Pakistan pointed that frequency of jellyfish blooms is increasing in Pakistan, like many other parts of the world. Such blooms, according to him disrupt the fishing industry by tearing nets and clogging cooling water intakes at power plants, causing power reductions or shutdowns.

According to Rab Nawaz, Senior Director Programmes, WWF-Pakistan, the 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.