Massive jellyfish blooms reported in the Arabian Sea | WWF
Massive jellyfish blooms reported in the Arabian Sea

Posted on 13 February 2020

Karachi, Feb 13: Large aggregations of jellyfish (Crambionella orsini) have been observed in the Arabian Sea and Gulf of Oman, seriously affecting major fishing operations in the area. As the bloom has become ubiquitous, fishing operations such as tuna gillnetting have practically stopped in offshore waters affecting livelihood of thousands of fishermen. Similarly, shrimp and fish trawling in coastal and offshore waters are being impacted, resulting in choking of trawl nets within a short span of time.

Earlier, jellyfish formed unprecedented blooms in the area in the years 2002 and 2003 which affected fishing operations in Iran, Oman and Pakistan. Research carried out by WWF-Pakistan indicated the reappearance of jellyfish Crambionella orsini in December 2019 in most parts of offshore waters of the Arabian Sea. It was feared that this could spread to vast area of the Arabian Sea, Gulf of Oman and Persian Gulf, which turned out to be true.
According to Muhammad Moazzam Khan, Technical Advisor (Marine Fisheries), WWF-Pakistan the jellyfish blooms, which indicate over-fishing, eutrophication, and climate change, are now frequently reported in most part of the world. In 2002 to 2003, Rhizostomatid jellyfish formed large-scale bloom all along the coast of Pakistan and seriously affected fishing operations. In December 2016, WWF-Pakistan reported a large bloom of jellyfish in offshore waters from Karachi to Ghora Bari, along the Sindh coast, and Ormara, along the Balochistan coast, which was caused by stinging jellyfish (Pelagia noctiluca) that clogged fishing nets. In addition, handling or removal of this jellyfish from fishing nets can inflict severe and painful stings. Fishermen involved in gillnetting and other fishing operations moved to other areas, and are now mainly operating in Sonmiani Bay and adjacent waters. According to Khan, the current bloom is distributed widely and has started spreading to beaches along the Sindh and Balochistan coast.
Khan further pointed out that based on circumstantial evidence, scientists acknowledge the need for more research in order to determine whether jellyfish blooms are a function of natural cycles or the result of human impacts on the environment. Jellyfish blooms, according to him feed on plankton, crustaceans, small fish and fish eggs, therefore, they deplete the food resources of fishes and even larger mammals like whales.  He emphasized the need to conduct a comprehensive research study on causes of these bloom formation.
Muhammad Ismail, a WWF-Pakistan trained skipper involved in tuna fishing for more than two decades, voiced concerns about the mass scale bloom of the jellyfish in offshore waters since December 2019. He has stopped fishing for the last two months and has been waiting, like 300 other skippers, for the situation to improve before resuming fishing. While, Sher Zamin Khan, another WWF-Pakistan trained skipper, shifted his tuna boat operation from Karachi to Gwadar but as the bloom spread all along the coast, he is now working on small fishing boats, which operate within the Gwadar Bay.
According to Dr. Babar Khan, Regional Head Sindh and Balochistan, WWF-Pakistan, the reasons for the sudden increase in the population of some jellyfish and forming of 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. Overfishing is also believed to increase jellyfish because it eliminates their predators and competitors.
Annually, about 2,500 metric tons (m. tons) of dried jellyfish is exported from Pakistan. Large jellyfish export was noticed during 2005 to 2007 when annually about 4,000 m. tons of jellyfish products were exported to China and Vietnam. Jellyfish fisheries in Pakistan is a source of extra income for small scale fisheries in coastal areas of Pakistan. It is estimated that more than 10,000 people are engaged in the fisheries in the country.
Specimen of jellyfish bloom in the Arabian Sea
© WWF-Pakistan